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KRRATPA. 

Page  7,  read  "Total  solids  for  Jersey  breed  15.40." 

Page  20,  line  7,  read  "less"  in  place  of  "  more." 

Page  23,  line  14,  "composite  sample,"  not  "  compositive." 

Page  43,  in  the  example,  read  "32^-4  =  8." 

Page  44.    "Total    solids  =:^^L+_^lZ/ 4- /  " 

Page  56,  reference  30,  "Hoard's  Dairyman." 
Page  133,  fifth  line  from  bottom,   "  i860"  not  "  18.60." 
Page  143.  "  timothy  hay"  read  "  pea  hay."     On  the  same  page 
the  figures  for  total  fat  should  read,  beginning  with  clover  hay  : 
"2.97,  2.75,  3.91,  1.50,  2.40,  2.80,  3.25,  2.93,  0.97,  1.40,  0.95,  1.57'." 
Digestible  fat,  sugar  beets,  and  mangels,  "o.i"  not  "i." 

Page  146,  the  corrected  reading  for  lactometer,   No.  32,  tem- 
perature 70,  is  "33.4"  not  "  34.4." 


E ASTON,  PA.: 

CHEMICAL  PUBLISHINO  CO. 

1897. 


. THE.  . 


CeiMlSTRI  OF  DAIRIING 


An  Outline  of  the  Chemical  and   Allied  Changes  Which  Take  Place  in 

Milk,  and  in  the  Manufacture  of  Butter  and  Cheese  ;  and 

the  Rational  Feeding  of  Dairy  Stock. 


HARRY  SNYDER,  B.S., 

Professor  of  Agricultural  Chemistry,  University  of  Minnesota,  and 
Chemist  of  the  Minnesota  Experiment  Station. 


EASTON,  pa.: 

CHEMICAL  publishing  CO. 
1897. 


Copyright,  1897.  by  Edward  Hart. 


PREFACE. 


These  notes  on  Dairy  Chemistry  were  originally  pre- 
pared for  classroom  use  in  the  School  of  Agriculture  of 
the  University  of  Minnesota.  They  are  based  on  a 
course  of  lectures  which  have  been  given  by  the  author, 
twice  a  year,  for  several  years  past. 

The  increased  interest  in  dairy  literature,  together 
with  the  scarcity  of  works  of  this  nature,  has  led  to  the 
belief  that  this  work  might  be  of  sufficient  value  to  war- 
rant its  publication.  In  its  preparation  free  use  has 
been  made  of  the  bulletins  and  reports  of  the  agricul- 
tural experiment  stations  of  the  various  states,  and  of 
the  standard  works  dealing  with  milk  and  its  products. 

These  notes  have  been  prepared  with  the  object  of 
furnishing  useful  information  to  a  class  of  young  men 
who  intend  to  become  farmers  and  dairymen  rather 
than  scientific  experts. 

Harry  Snyder. 

College  of  agriculture, 
University  of  Minnesota, 
St.  Anthony  Park,  Minn. 
October  31,  1896. 


CONTENTS, 


CHAPTER  I. 

The  General  Composition  of  Milk,  pp.  2-13. — Total  solids  ; 
Ash;  Casein;  Albumin;  Milk  sugar  ;  Milk  fats;  The  average 
composition  of  milk  ;  The  fat  globules ;  Variations  in^the  size  of 
the  fat  globules  ;  Surface  tensions ;  Total  yield  of  milk ;  First 
milk  and  strippings.  The  milk  serum,  constancy  in  composi- 
tion of.    References  to  Chapter  I. 

CHAPTER  II. 

Milk  Testing,  pp.  14-26. — The  object  of  testing  milk ;  The 
reliability  of  the  Babcock  milk  test ;  Sampling  milk  ;  Measur- 
ing milk  with  the  pipette  ;  The  test-bottles ;  The  acid  ;  The 
separation  of  the  fat  by  the  centrifugal ;  Reading  the  amount  of 
fat ;  The  use  of  dividers  in  reading  the  test ;  Speeding  the 
machine  ;  Centrifugal  action  ;  Composite  test ;  Testing  skim- 
milk  ;  Sampling  frozen  milk ;  Apparatus  for  measuring  the 
acid.    References  to  Chapter  II. 

CHAPTER  III. 

Milk  Fats,  pp.  27-32. — The  composition  of  fat;  Butter-fat 
composed  of  a  number  of  separate  fats  ;  The  composition  of  milk 
fats;  Palmatin  ;  Stearin;  Olein  ;  Butyrine ;  Glycerine,  a  part 
of  all  fats ;  Food  value  of  fat ;  Saponification ;  Comparative 
characteristics  of  butter  and  oleomargarin.  References  to 
Chapter  III. 

CHAPTER  IV. 

3filk  Sugar  and  Lactic  Acid,  pp.  33-39. — Physical  properties 
of  milk  sugar  ;  The  fermentation  of  milk  sugar ;  The  necessary 
conditions  for  the  fermentation  ;  The  chemistry  of  the  action  ; 
The  ripening  of  cream ;  Determining  the  lactic  acid  in  milk. 
References  to  Chapter  IV. 

CHAPTER  V. 

The  Lactometer  and  the  Detection  of  Adulterated  Milk,  pp. 
40-45. — The  specific  gravity  of  milk  ;  The  workings  of  the  lac- 
tometer ;  Lactometer  results  liable   to   error  ;  Effects   of  tern- 


CONTENTS.  V 

perature  upon  the  lactometer  readings  ;  Different  forms  of  lactom- 
eters ;  The  normal  specific  gravity  of  milk  ;  Skim-milk  and 
watered  milk  ;  Combined  use  of  the  Babcock  test  and  lactome- 
ter in  determining  the  character  of  milk;  Formulas  for  deter- 
mining the  per  cent,  of  solid  matter  in  milk.  References  to 
Chapter  V. 

CHAPTER  VI. 

The  Chemistry  of  Butter-Making,  pp.  46-57.— Composition 
of  cream  ;  Testing  cream ;  The  recovery  of  fat  in  cream  ;  Losses 
of  fat  by  different  methods  of  creaming  compared  ;  Necessary 
conditions  for  creaming  by  the  cold,  deep-setting  process  ;  Good 
creaming  conditions  and  poor  creaming  conditions  compared  ; 
Distribution  of  the  milk  solids  in  butter-making;  Churning; 
The  composition  of  butter;  Factors  which  affect  the  composi- 
tion of  butter.    References  to  Chapter  VI. 

CHAPTER  VII. 

TheChemistry  of  Cheese-Making ,  pp.  58-77. — The  nitrogenous 
compounds  of  milk;  Casein;  Albumin;  Rennet;  The  rennet 
test ;  The  hot  iron  test  ;  The  process  of  cheese-making  briefly 
described  ;  Blank  form  of  cheese  report  ;  Distribution  of  milk 
solids  in  cheese-making ;  Examples  of  different  types  of  milk 
used  for  making  cheese  and  the  losses  of  fat  and  solids  ;  Amount 
of  cheese  made  from  different  types  of  milk  ;  Composition  of 
cheese  made  from  different  milks  ;  The  testing  of  cheese  by  the 
Babcock  test  ;  The  ripening  of  cheese  ;  Factors  influencing  the 
ripening  of  cheese  ;  The  hygrometer  and  its  use  in  the  curing 
room  ;  Paying  for  milk  by  test  in  cheese  factories  ;  Comparative 
amount  of  butter  and  cheese  made  from  the  same  and  different 
grades  of  milk.     References  to  Chapter  VII. 

CHAPTER  VIII. 

The  Ash  and  Miscellaneous  Compounds  of  Milk,  pp.  78-85. 
— The  amount  of  ash  in  milk  ;  The  composition  of  the  ash  ; 
The  function  of  milk  ash  ;  Citric  acid  in  milk  ;  Colostrum  milk, 
its  properties  and  composition ;  Colostrum  cells  and  supposed 
origin  ;  The  effects  of  colostrum  upon  the  quality  of  butter  and 
cheese;  Tyrotoxicon  ;  Effects  of  tyrotoxicon  upon  health  ;  Urea 
in  milk;  Fibrin  in  milk ;  Supposed  effects  of  fibrin  upon  the 
creaming  of  milk  by  the  gravity  process  ;  The  gases  in  milk, 
their  nature  and  effects  upon  milk  ;  The  color  of  milk ;  The 
color  of  milk  not  alwaj^s  an  index  to  its  fat  content ;  Butter 
colors,  their  composition  and  use.    References  to  Chapter  VIII. 


VI  CONTENTS. 

CHAPTER  IX. 

Dairy  Salt  and  Commercial  Problems  Relating  to  Milk,  pp. 
86-92. — Large  aud  small-sized  salt  crystals;  Properties  of  a 
good  salt ;  Tests  for  a  good  salt ;  Changes  in  the  fat  content  of 
milk  during  transportation  ;  Effects  of  delayed  setting  and 
cooling  upon  the  creaming  properties  of  milk  ;  A  delayed  set- 
ting undesirable  on  account  of  fouling  the  milk  ;  Aerating  milk  ; 
Effects  of  one  cow's  milk  upon  the  creaming  of  another  cow's 
milk;  Cream  raising  by  dilution;  Dilution  undesirable  on  ac- 
count of  heavy  loss  of  fat ;  Hot  water  dilution  causes  over- 
ripening  of  the  cream  ;  Decreased  feeding  value  of  the  diluted 
skim-milk  ;  Effects  of  dilution  upon  the  volume  of  cream.  Ref- 
erences to  Chapter  IX. 

CHAPTER  X. 

The  Sanitary  Condition  of  Cow's  Milk  and  the  Milk  of  Other 
Domestic  Animals,  pp.  93-99. — The  constancy  in  composition  of 
the  milk  from  a  healthy  cow;  Milk  from  diseased  cows  ;  Mam- 
metis  ;  pneumonia,  tuberculosis  deposits  in  both  lungs  and  udder, 
inflammation  of  the  udder ;  The  microscopic  appearance  of 
diseased  milk  ;  Milk  as  a  medium  for  the  spreading  of  disease  : 
Factors  which  influence  the  sanitary  condition  of  milk  ;  A  dis- 
eased cow  may  give  apparently  healthy  milk  ;  Effects  of  dirt 
and  decomposing  matter  upon  the  quality  of  butter  or  cheese 
produced  ;  Milk  of  other  domestic  animals ;  Mare's  milk, 
sow's  milk  and  sheep's  milk;  Special  peculiarities  in  the  com- 
position of  each.    References  to  Chapter  X. 

CHAPTER  XI. 

Preserving  Milk,  pp.  100-105.— Principles  involved  in  the 
various  methods  proposed  for  preserving  milk  ;  Effects  of  high 
temperature  ;  Sterilizing  milk,  directions  for  ;  Sterilized  milk 
and  pure  unsterilized  milk  compared  as  to  sanitary  value; 
Pasteurizing  milk,  principles  involved  and  methods  employed  ; 
Use  of  chemicals  for  preserving  milk,  why  objectionable  ;  Con- 
densed milk.    References  to  Chapter  XI. 

CHAPTER  XII. 

The  Composition  of  Skim-milk,  Buttermilk  and  Whey,  pp. 
106-111.— Skim-milk,  its  composition  ;  Skim-milk  more  concen- 
trated in  ash,  casein,  albumin  and  sugar  than  the  original  whole 
milk;  Skim- milk,  etc.,  aid  in  making  other  food  digestible; 
Skim-milk  alone  an  incomplete  food  ;    Comparative  food  value 


CONTENTS.  Vll 

of  sweet  and  sour  skim-milk  ;  Old  and  over  fermented  skim- 
milk  may  cause  diarrhea  ;  Comparative  composition  of  skim- 
milk,  buttermilk  and  whey  ;  Action  of  sour  whey,  etc.,  upon 
iron,  tin,  zinc  and  wood  ;  Whey  causes  rapid  rotting  of  wood  ; 
Separator  skim-milk  sours  very  rapidly.  References  to  Chapter 
XII. 

CHAPTER  XIII. 

Other  Simple  Methods  Etnployed  in  Milk  Testing,  and  the 
Adulteration  of  Dairy  Products,  pp.ii2-ii8. — Why  the  Babcock 
test  is  generally  used;  Beimling's  method;  The  lactocrite  ; 
Short's  method  ;  Gerber'sbutyrometer;  Cochrane's  method  ;  The 
lactoscope  and  pioscope  unreliable  ;  The  gravimetric  methods 
employed  by  chemists;  Artificial  butter  products,  sources  of  fat 
in  ;  Cheese,  skim-milk,  and  filled  ;  Simple  method  for  testing 
butter-fat;  Testing  filled  cheese;  The  injury  of  adulterated 
dairy  products  to  the  dairy  industry  ;  The  digestibility  of  adul- 
terated dairy  products.    References  to  Chapter  XIII. 

CHAPTER  XIV. 

The  Effects  of  Food  upon  the  Quality  of  Dairy  Products,  pp. 
1 19-124. — The  quality  of  milk  fats  capable  of  being  influenced 
more  than  the  percentage  amount;  Fat  in  milk  not  produced 
direct  from  fat  in  food  ;  The  fat  and  other  compounds  of  the  food 
may  influence  the  composition  of  the  fat  produced  in  the  milk  ; 
Effects  on  quality  of  milk  fats  when  cotton-seed  meal,  linseed 
meal,  corn  meal,  oats,  etc.,  are  fed ;  Effects  of  balanced  and  un- 
balanced rations  upon  the  quality  of  fat  produced  in  the  milk  ; 
Effects  of  coarse,  rough  fodders,  ensilage  and  potatoes  ;  Effect 
of  rye  fodder  on  taste  of  milk  ;  Effect  of  weeds,  as  wild  garlic, 
mustard,  turnips,  rape,  etc.  ;  Cause  of  good  and  bad  flavors  in 
butter  and  cheese.     References  to  Chapter  XIV. 

CHAPTER  XV. 

The  Composition  of  Fodders  and  the  Calculation  of  Rations, 
pp.  125-137. — Importance  of  the  subject ;  Uses  of  the  food  by  the 
body  ;  Heat-producing  and  tissue-renewing  foods  ;  Balanced 
rations  ;  Explanation  of  terms  used  relating  to  the  composition 
of  food-stuffs  :  water,  dry  substance,  ash,  non-nitrogenous  com- 
pounds, ether  extract,  fiber,  nitrogen-free  extract,  nitrogenous 
compounds,  the  different  kinds  of;  Protein;  Crude  protein; 
Importance  of  protein  ;  Digestible  nutrients ;  Nutritive  ratio ; 
Heat  units  ;  Standard  ration ;  How  to  calculate  a  ration  ;  Roots 


Vlll  CONTENTS. 

or  silage  desirable  in  a  ration  ;  Bulky  and  concentrated  rations  ; 
Requirements  of  different  animals  ;  The  comparative  cost  and 
value  of  fodders  and  grains.     References  to  Chapter  XV. 

TABLES. 

Average  composition  of  American  feeding  stuffs,  pp.  138-141  ; 
Average  composition  of  Minnesota  feeding  stuffs,  pp.  142-143; 
Market  price  and  food  value,  p.  144;  Tables  for  correcting  lac- 
tometer number  of  milk  according  to  temperature,  pp.  145-146. 

APPENDIX. 
Revievi^  questions  for  classroom  use,  pp.  147-15 1. 


The  Chemistry  of  Dairying. 

INTRODUCTION. 

Dairy  Chemistry  is  that  part  of  agricultural  chemis- 
try which  treats  of  the  chemical  and  allied  changes 
that  take  place  in  milk,  and  in  its  manufacture  into 
butter  and  cheese.  Each  operation  in  the  dairy,  as 
creaming,  ripening  the  cream,  churning,  cheese-mak- 
ing, etc.,  involves  chemical,  physical,  and  bacteriolog- 
ical changes,  a  knowledge  of  which  is  essential  in  order 
to  understand  and  properly  control  many  of  the  opera- 
tions of  both  cheese-making  and  butter-making.  The 
chemical,  bacteriological,  and  physical  changes  which 
take  place  in  butter-  and  cheese-making  are  so  closely 
allied  that  it  is  difficult  to  treat  of  one  without  also 
considering  the  others.  Our  present  knowledge  of  many 
of  the  changes  which  milk  and  its  products  undergo  in 
their  preparation  for  the  market,  is  incomplete  ;  there 
are,  however,  many  facts  which  are  known  and  under- 
stood, and  if  they  were  carefully  observed  and  properly 
made  use  of  by  the  butter-  and  cheese- maker,  a  better 
quality  of  products  could  be  more  generally  produced. 
Before  taking  up  the  study  of  milk  and  its  products,  it 
is  first  necessary  to  obtain  a  clear  conception  of  the 
nature  and  composition  of  milk,  and  then  the  separate 
operations  in  the  dairy  may  be  studied  in  detail. 


CHAPTER  I. 
The  General  Composition  of  Milk. 

Milk  is  a  very  complex  material.  It  is,  in  fact,  one 
of  the  most  complex  of  the  animal  fluids.  Milk  is  com- 
posed of  a  number  of  solid  substances  dissolved  and  sus- 
pended in  water.  The  substances  in  solution  are  : 
casein,  ash,  sugar,  and  albumin.  These  substances, 
together  with  the  water  in  which  they  are  dissolved 
constitute  the  milk  serum.  The  fat  in  the  milk  is  not 
dissolved,  but  is  suspended  in  the  milk  serum.  The  fat 
is  present  in  the  form  of  globules,  like  little  rubber  balls. 
Total  Solids. — The  total  solids  of  milk  are  what  re- 
main after  all  of  the  water  has 
been  removed.  The  term  dry 
matter  is  sometimes  used  in- 
stead of  total  solids.  The  sol- 
ids are  obtained  by  evapora- 
ting a  portion  of  milk  to  com- 
plete dryness  at  the  tempera- 
ture of  boiling  water. 

In  the  illustration  observe 
that  the  milk  is  placed  in  the 
dish  which  is  supported  over 
boiling  water.     The  milk  is 
^^^-  ^-  heated,  by  the  steam,  to  a  tem- 

perature of  212°  F.,  when  the  water  in  the  milk  is  ex- 
pelled as  steam.     The  residue  left  in  the  dish,  known 

Twnxn  imunr 
N.  C.  FUt,t»  PmIi^^ 


ASH. 


as  the  milk  solids,  is  a  shiny,  brittle  mass  composed  of 
fat,  milk-sugar,  ash,  casein,  albumin,  and  many  other 
compounds.  When  all  of  the  water  is  removed  from 
ICO  pounds  of  milk,  about  thirteen  pounds  of  solid  mat- 
ter will  be  left.  The  milk  of  some  cows  contains  more 
solid  matter  than  that  of  others.  There  is  rarely  less 
than  twelve  pounds  or  more  than  sixteen  pounds  of 
solids  in  loo  pounds  of  milk.  In  tables  of  analyses 
this  is  usually  stated  as  per  cent,  of  total  solids,  that  is, 
pounds  of  solid  matter  in  lOo  pounds  of  milk. 

2.  Ash. — The  ash  is  what  remains  after  the  solid  mat- 
ter of  milk  has  been  burned. 
It  is  a  grayish  white  material. 
The  ash  in  the  milk  is  very 
valuable  for  the  formation  of 
bones.  lOo  pounds  of  milk 
will  yield  about  three-fourths 
of  a  pound  of  ash.  or  seventy- 
five  hundredths  per  cent.  ash. 
The  ash  in  milk  is  very  con- 
stant and  varies  but  little  from 
three-quarters  of  one  per  cent. 

In  order  to  obtain  the  ash, 
the   little   fiat-bottomed   dish 
"a"  is  placed  on  the  triangle .L      ^  __^- 
"b"  over  the  gas  flame.    The  Fig.  2. 

sugar,  fat,  casein,  and  albumin  are  burned  and  converted 
into  volatile  (smoke-like)  products,  while  the  ash  is  left 
as  a  grayish  white  powder  in  the  dish. 

When  the  milk  is  analyzed  in  the  laboratory  the  little 


4  THE    CHEMISTRY   OF   DAIRYING. 

dish,  which  is  used  for  determining  the  solids  and  ash,  is 
carefull}'  weighed  on  a  ver\^  delicate  pair  of  scales.  A 
small  quantity  of  milk,  after  it  has  been  carefully 
weighed,  is  put  into  the  dish.  The  water  is  expelled 
from  the  milk  in  the  way  explained,  and  after  careful 
drying,  the  dish  with  the  milk  solids  is  weighed.  The 
increase  in  weight  is  that  of  the  milk  solids  obtained 
from  the  milk  used,  which  was  also  weighed.  That  is, 
a  weighed  quantity  of  milk  has  given  a  weighed  quantity 
of  milk  solids.  The  corresponding  amount  of  solids  in 
I  GO  parts  of  milk  is  then  obtained  b}^  a  simple  proportion. 

Example. — Dish  weighs  12.850  grams,  milk  used  weighs  10.51 
grams.  The  dish  and  milk  solids  weigh  14.195  grams.  The  dish 
and  milk  ash  weigh  12.925  grams.  What  is  the  percent,  of  solids 
in  this  milk  ?     What  is  the  per  cent,  of  ash  ? 

Grams. 

Dish  and  solids 14. 195 

Dish 12.850 

Solids  in  10.51  grams  milk 1-345 

Grams. 

Dish  and  milk  ash 12.925 

Dish 12.850 

Milk  ash  in  10.51  grams  milk 0.075 

In  100  grams  of  milk,  how  many  grams  of  solids? 
1.345  :  10.51  :  :  .^jr :  100 

X  =  12.80  or  12.80  per  cent,  solids  in  the  milk. 
In  100  grams  of  milk,  how  many  grams  of  ash  ? 
0.075  :  10.51  w  X  :  100. 

;r  =  o.7i  or  0.71  per  cent,  ash  in  the  milk. 

3.  The  Casein  in  flilk  is  generall}^  know^n  as  the  curd, 
and  when  obtained  from  the  milk  in  a  pure  state,  it  is  a 


MILK    FATS.  5 

grayish  white  powder.  Casein  takes  a  very  important 
part  in  cheese-making  and  other  dairy  operations.  The 
chemical  and  physical  properties  of  casein  will  be 
studied  in  detail  further  on.  Casein  is  very  valuable  as 
food.  There  is  not  as  much  casein  in  milk  as  there  is 
fat.  One  hundred  pounds  of  milk  will  ordinarily  con- 
tain about  three  pounds  of  casein.  The  per  cent,  of 
casein  in  milk  is  quite  constant,  ranging  from  two  and 
nine-tenths  to  three  and  six-tenths  per  cent. 

4.  Albumin,  which  is  nearly  identical  with  the  white 
of  the  egg,  is  also  found  in  milk.  Albumin  has  about 
the  same  general  composition  as  casein.  The  "  scum" 
which  forms  when  milk  is  boiled  is  albumin.  There  is 
from  a  half  to  three-quarters  of  a  pound  of  albumin  in 
every  100  pounds  of  milk. 

5.  Milk  Sugar. — There  is  present  in  milk  a  material 
called  milk  sugar,  which,  in  general  appearance,  resem- 
bles confectionary  sugar.  Milk  sugar  possesses  no 
sweet  taste.  Indirectly,  the  milk  sugar  takes  a  very 
important  part  in  both  butter-  and  cheese-making. 
There  is  from  four  and  three-fourths  to  five  pounds  of 
milk  sugar  in  every  100  pounds  of  milk. 

6.  riilk  Fats.— The  fat  in  milk  is  familiar  as  the 
product  obtained  as  butter  from  the  churn.  Milk  fats 
and  butter,  however,  are  not  the  same.  By  milk  fats  is 
meant  the  pure  dry  fat,  free  from  water,  salt,  or  casein, 
while  butter  contains  all  three  of  these  materials.  One 
hundred  pounds  of  butter  contain  about  eighty-three 
pounds  of  pure  dry  fat. 


6  THE    CHEMISTRY    OF    DAIRYING. 

Each  one  of  these  separate  compounds  in  milk  will  be 
studied  in  detail.  In  beginning  the  study  of  this  sub- 
ject, the  student  should  aim  to  obtain  first  a  general 
idea  of  the  composition  of  milk,  and  then  later  to  study 
the  separate  compounds  in  detail. 

Milk  varies  in  composition  according  to  the  special 
peculiarities  of  the  cow  as  to  the  breed,  nature  of  the 
food,  and  period  of  lactation. 

The  average  composition  of  3000  samples  of  milk  com- 
piled from  analyses  reported  in  the  agricultural  exper- 
iment station  reports  and  bulletins  of  the  various  states, 
gives  approximately  : 

Per  cent. 

Water 87.50 

Total  solids 12.50 

Fats 3.60 

Solids  not  fat 8.90 

Casein  and  Albumin 3.40 

Milk  sugar 4.75 

Ash 0.75 

As  an  example  of  milk  from  a  good  herd,  the  average 
analyses  of  112  samples  from  the  dairy  herd  of  the  Min- 
nesota Experiment  Station  in  1893,  gave  : 

Average.    Highest.     I,owest. 
Per  cent.    Per  cent.    Per  cent. 

Water 86.32  87.82  84.76 

Total  solids 13.68  15.24  12.18 

Fat 4.74  6.50  3.45 

Solids  not  fat 8.94  9.74  8.73 

Casein  and  albumin ... .  3.42  4.20  3.00 

Milk  sugar 4,85  5.25  4.30 

Ash 0.67  0.78  0.60 

Inasmuch  as  the  per  cent,  of  fat  as  given  in  the  pre- 


MILK    FATS.  7 

ceding  table  is  somewhat  greater  than  is  usually  pro- 
duced by  an  ordinary  herd,  the  average  of  the  analyses 
of  43  samples  of  milk  from  different  herds  in  the  same 
state  are  given : 

Per  cent. 

Water  .     87.20 

Total  solids 12.80 

Fats 3.65 

Solids  not  fat 9.15 

Casein  and  albumin 3.57 

Milk  sugar 4.85    ■■,  .[.& 

Ash 0.71 

The  composition  of  the  milk  from  different  breeds,  as 
given  by  the  New  York  Experiment  Station  for  one 
year,  was  : 

Total  Milk 

Breeds.  solids.  Fat.        Casein,      sugar.        Ash. 

Per  cent.  Per  cent.  Per  cent.  Per  cent.  Per  cent. 

Holstein-Fresian..   12.39        3-46        3-39        4.84        0.74 

Ayrshire 13.06        3.57         3.43         5.33         0.70 

Jersey 10.40        5.61         3.91         5.15         0.74 

Am.  Holderness..   12.63        3.55        3.39        5.01        0.70 

Guernsey 14.60        5.12         3.61         5. 11         0.75 

Devon 13.77        4-15        3-76        5-07        0.76 

These  figures  are  not  necessarily  true  for  all  cases, 
because  there  is  frequently  as  great  a  difference  in  the 
composition  of  milk  from  cows  of  the  same  breed  as  be- 
tween the  cows  of  different  breeds.  These  figures  are 
given  mainly  for  illustration.  The  student  should  re- 
member the  general  figures  as  : 

Solids,  twelve  to  thirteen  per  cent.,  occasionally  as 
high  as  fifteen  per  cent. 

Fat,  three  to  four  per  cent.,  occasionally  as  high  as 
five  or  six  per  cent. 


8  THE    CHEMISTRY   OF   DAIRYING. 

Casein  and  albumin,  three  and  one-fourth  to  three 
and  three-fourths  per  cent. 

Sugar,  four  and  three-fourths  to  five  and  one-fourth 
per  cent. 

Ash,  0.75  per  cent. 

7.  The  Fat  Globules. — The  fat  globules  in  milk  are 
very  small.  It  would  require  on  an  average  about  5,000 
of  them  to  measure  an  inch.  A  cubic  millimeter  of  milk 
is  estimated  to  contain  from  2,000,000  to  4,000,000 
fat  globules.  Under  the  microscope  the  fat  globules 
appear  grouped  together  in  small  colonies.  The  size 
of  the  fat  globules  varies  with  ( i )  the  breed  and  the  in- 
dividuality of  the  animal,  and  (2)  according  to  the 
length  of  time  that  the  animal  has  been  in  milk.  When 
a  cow  is  fresh  there  is  a  smaller  number  of  large  glob- 
ules ;  when  the  cow  is  well  along  in  her  milking  period 
the  globules  are  smaller,  and  at  the  same  time  they  are 
more  numerous.  These  small  bodies  are  the  bodies 
which  must  be  massed  together  and  collected  when  but- 
ter is  made.  The  more  completely  they  are  recovered 
the  greater  will  be  the  amount  of  butter  produced.  The 
globules  are  simply  solid  masses  of  fat.  At  one  time  it 
was  supposed  that  the  fat  globules  were  surrounded  by 
a  membrane,  and  in  churning  it  was  supposed  the  mem- 
brane had  to  be  broken  before  the  globules  would  mass. 
Recent  chemical  investigations  have  shown  that  there 
is  no  membrane  surrounding  the  fat  globules. 

8.  Surface  Tension. — The  fat  globules  are  lighter 
than  any  of  the  constituents  of  the  milk  serum.  The 
globules  retain  their  form  and  individuality  on  account 


.^v 


'r^iP: 


f\ 


w<:. 


0/*l' 


The  Fat  Globulks  of  Fresh  Milk        x  300. 


TOTAL  YIELD.  •  9 

of  the  surface  tension.  The  surface  tension  is  the  pres- 
sure that  is  exerted  on  the  surface  of  the  globules, 
and  is  equal  on  all  sides,  hence  the  spherical  form  of 
the  globules. 

The  illustration  ( Fig .  3  )  shows  the  composition  of  milk . 


Caae/'n  MilkSugar  /l/bumin      fleh 

Fig.  3- 

If  the  first  tube  were  filled  with  milk,  the  corresponding 
amounts  of  the  other  constituents  would  be  as  repre- 
sented. 

9.  Total  Yield  in  Pounds,  and  Percentage  Composi= 
tion. — The  total  jaeld,  in  pounds,  of  milk  solids,  and  fat 
produced  in  a  given  time  is  of  more  importance  than  the 
percentage  composition,  and  it  is  the  basis  on  which  all 
comparisons  are  usually  made.  The  total  yield  in 
pounds  of  each  constituent  is  obtained  by  multiplying 
the  percentage  composition  by  the  total  weight  of  milk. 
For  example,  two  cows  gave,  for  one  week,  an  average 
yield  of  thirty- three  and  thirty-five  and  two- tenths  pounds 
respectively  of  milk.  The  average  composition  of  the 
milk  for  this  period  was  as  given  below.     The  pounds  of 


lO  THE    CHEMISTRY    OF    DAIRYING. 

each  of  the  constituents  are  found  by  multiplying  the 
percentage  composition  by  the  weight  of  the  milk. 

Cow  No.  I. 

Composi-        Pounds  Total  pounds 

tion.  milk.  given. 

Total  solids  0.1344  X  33  =  4.44  total  solids. 

Fats   0.0466  X  33  =  1.54  fats. 

Ash 0.0068  X  33  ^  0.22  ash. 

Casein,  etc  0.0334  X  33  =  1. 10  casein,  etc. 

Milk  sugar  0.0475  X  33  =  1.56  milk  sugar. 

Cow  No.  2. 

Composi-         Pounds  Total  pounds 

tion.  milk.  given. 

Total  solids  0.1256  X  35-2  =    4.42  total  solids. 

Fats 0.0406  X  35.2  =    1.43  fats. 

Ash 0.0064  X  35-2  =    0.23  ash. 

Casein,  etc  0.0304  X  35.2  =    1.07  casein. 

Milk  sugar  0.0478  X  35.2  =    1.68  sugar. 

10.  First  Milk  and  Strippings. — As  is  well  known, 
the  first  portion  of  milk  given  by  any  cow,  at  any  milk- 
ing, is  poor  in  fat,  while  the  last  portion,  or  strippings, 
is  very  rich  in  fat;  the  amount  of  casein,  ash,  and  sugar 
is  about  the  same  in  both  cases.  The  composition  of 
the  first  pint  and  the  last  pint,  in  the  case  of  the  two 
cows  previously  mentioned,  well  illustrates  this  point. 

Cow  No.  I.  Cow  No.  2. 

First  pint.  I^ast  pint.  First  pint.   Last  pint. 

Percent.  Percent.  Percent.    Percent. 

Total  solids 9.42         19.49  10,10         18.47 

Fat 0.71         10.84  1.02  9.49 

Solids   not  fat-...   8.71          8.65  9.08  8.98 

Ash 0.68          0.72  0.70  0.74 

Casein,  albumin-.  3.44          3.51  3.35  3.65 


MILK   SERUM.  II 

II.  Milk   Serum,   Constancy   of  Composition The 

solids  of  the  milk  serum  are  fairly  constant  in  composi- 
tion. This  is  well  illustrated  in  the  case  of  the  composi- 
tion of  the  first  milk  and  the  strippings.  The  solids  of 
the  milk  serum,  also  known  as  the  solids  not  fat,  are 
never  less  than  8.25  per  cent,  and  rarely  more  than  9.75 
per  cent.  The  average  is  about  nine  per  cent.  The 
greatest  difference  in  the  composition  of  various  milks 
is  observed  in  the  amount  of  fat  that  is  present. 
Any  material  increase  in  the  total  solid  matter  of  milk 
is  due  mainly  to  an  increase  of  the  fat.  The  solids  not 
fat  are  subject  to  but  slight  variations  compared  with 
the  fluctuations  of  the  fat. 

Nearly  all  of  the  important  fluids  of  the  body,  like  the 
blood,  etc.,  are  normally  quite  constant  as  to  chemical 
composition.  With  milk,  the  constancy  of  its  composi- 
tion is  confined  to  the  solids  of  the  milk  serum. 


REFERENCEvS  TO  CHAPTER  I. 

[Note.— The  references  given  at  the  end  of  each  chapter  are  not  intended 
as  a  complete  index  of  the  literature.  They  are  given  as  a  guide  for  those 
who  desire  to  make  a  more  thorough  study  of  the  subject.] 

1.  The  Composition  of  Milk.  Konig :  Chemie  der  Mensch- 
lichen.     Nahrungs-  uud  Genussmittel. 

2.  The  Composition  of  Cow's  Milk.     Blyth  :  Food  Analysis. 

3.  The  Physical  Composition  of  Milk.  Duclaux  :  Le  I^ait, 
Etudies  Chemiques  et  Microbiologiques. 

4.  The  Composition  of  Milk.  Minnesota  Experiment  Station, 
Bulletin  No.  19. 

5.  The  Constitution  of  Milk.  Wisconsin  Experiment  Station, 
Bulletin  No.  18. 

6.  The  Composition  of  Milk  and  Its  Products.  Richmond  : 
Analyst,  August,  1894. 


12  THE    CHEMISTRY   OF   DAIRYING. 

7.  The  Composition  of  Milk  as  Affected  by  Change  of  Milkers 
and  Change  of  Quarters.  Wisconsin  Experiment  Station  Re- 
port, 1889. 

8.  Variations  in  the  Fat  Content  of  Milk.  Weilandt :  Milch 
Zeitung,  24,  (^1895). 

9.  The  Average  Composition  of  Milk.  Vieth :  Analyst,  18^ 
192,  193. 

10.  Historical  Article  Regarding  Milk.  Blyth  :  Food  Analy- 
sis. 

11.  The  Composition  of  Milk  from  Different  Breeds.  Michi- 
gan Experiment  Station,  Bulletin  No.  68. 

12.  The  Composition  of  Milk  from  Different  Breeds.  New 
York  State  Station  Report,  1891. 

13.  The  Composition  of  Milk.  Maine  Experiment  Station 
Report,  1893. 

14.  Variations  in  Milk  During  the  Period  of  Lactation.  Ver- 
mont Experiment  Station,  Sixth  Annual  Report. 

15.  Composition  of  Milk.  Wisconsin  Experiment  Station  Re- 
port, 1889;  also  Bulletins  Nos.  15  and  16. 

16.  Composition  of  Milk.  New  Jerse}'^  Experiment  Station, 
Bulletins  Nos.  61,  65,  68,  77. 

17.  Composition  of  Milk.  Massachusetts  State  Station  Re- 
ports, 1888,  1889,  1890,  1891,  1892. 

18.  Composition  of  Milk.  Maine  Experiment  Station  Report, 
1890. 

19.  Variations  in  Milk.  Wisconsin  Experiment  Station, 
Fifth  Annual  Report. 

20.  The  Number  and  Size  of  Fat  Globules  in  Milk.  Wisconsin 
Experiment  Station  Report,  1890. 

21.  The  Fat  Globules  of  Milk.  Maine  Experiment  Station, 
Annual  Report,  1890. 

22.  Conditions  Influencing  the  Number  and  Size  of  the  Fat 
Globules.     Milch  Zeitung,  24,  (1895). 

23.  On  the  Variation  in  the  Number  and  Size  of  Fat  Globules. 
Pennsylvania  Experiment  Station  Report,  1895. 


REFERKNCES  TO   CHAPTER    I.  13 

24.  The  Size  of  Fat  Globules  in  Milk.  Vermont  Experiment 
Station,  Fourth  Annual  Report. 

25.  Size  of  Fat  Globules  in  the  First  and  Last  Half  of  Milking. 
Indiana  Experiment  Station,  Bulletin  No.  24. 

26.  The  Size  of  Fat  Globules  in  Milk  of  Cows  of  Different 
Breeds.  New  York  State  Experiment  Station  Reports,  1891, 
1892. 

27.  Composition  of  First  Milk  and  Strippings.  Connecticut 
State  Experiment  Station  Report,  1886. 

28.  Grouping  of  the  Fat  Globules.  Wisconsin  Experiment  Sta- 
tion, Bulletin  No.  18. 

29.  Grouping  of  the  Fat  Globules.  Heidenhain,  in  Hermanns' 
Hand-book. 

30.  Fore  Milk  and  Strippings.     Blyth  :  Food  Analysis. 

31.  Relation  of  Fat  and  Casein  in  Milk.  Vermont  Experiment 
Station,  Fourth  Annual  Report. 

32.  Liquid  Condition  of  the  Fat.  Soxhlet  :  Landswirtschaft- 
lichen  Versuchs-Stationen,  1876. 

33.  No  Membrane  about  Milk  Fat  Globules.  Martiny  :  Die 
Milch. 

34.  Artificial  Emulsions  Representing  Milk.  Duclaux :  An- 
nales  de  1'  Institute  Nat.  agronomique,  1882. 

35.  The  Membrane  of  the  Milk  Fat  Globule.  Jurstenburg: 
Die  Milch  drusen  die  Kuh. 

36.  The  Membrane  of  the  Fat  Globule.  Bechamp  :  Comptes 
Rendus,  1888. 

37.  Fleischmann  :  Lehrbuch  der  Milchwirtschaft. 

38.  Scholl  :  Die  MilcTi. 

39.  Kirchner  :  Handbuch  der  Milchwirtschaft. 

40.  Martiny  :  Die  Milch. 

41.  Milk.  Article  in  Hand-book  of  Experiment  Station  Work, 
United  States  Department  of  Agriculture. 


CHAPTER  II. 
Milk  Testing. 

A  knowledge  of  the  amount  of  fat  in  milk  is  essential 
in  order  to  determine  :  ( i )  Any  unnecessary  waste  in 
the  manufacture  of  butter  and  cheese  ;  (2)  to  determine 
the  value  of  individual  cows;  (3)  to  serve  as  a  basis  for 
the  purchasing  of  milk  ;  and  (4)  to  determine  the  cost 
of  production  of  milk. 

A  number  of  simple  methods  have  been  proposed  for 
testing  milk  ;  some  of  them  require  a  more  extended 
knowledge  of  chemical  operations  than  others.  The 
method  which  is  most  generally  used,  on  account  of  its 
accuracy  and  simplicity,  is  the  Babcock  centrifugal 
method. 

12.  Reliability  of  the  Babcock  flethod. — This  method 
has  been  carefully  tested  by  many  chemists,  and  in  all 
cases  has  been  found  to  be  a  reliable  test.  There  is  a 
tendency  to  read  the  results  too  low  ;  this  will  be  spoken 
of  more  in  detail  when  dealing  with  that  part  of  the  oper- 
ation. In  the  case  of  skim-milk  and  buttermilk,  when 
the  fat  present  is  less  than  two-tenths  per  cent,  (one 
small  division) ,  the  method  does  not  always  give  reliable 
results.  This  does  not  impair  its  usefulness,  because 
frequently  the  losses  are  greater  than  this,  and  so  far  as 
the  whole  milk  is  concerned  the  method  is  perfectly  re- 
liable. When  the  Babcock  test  shows  only  a  trace  of 
fat  in  the  skim-milk  or  buttermilk,  the  losses  are  very 
small. 


SAMPLING   MILK. 


15 


13.  Sampling  Milk. — Every  lot  of  milk,  whether  a 
large  or  small  one,  should  be  weighed  before  sampling. 
The  milk  as  it  comes  from  the 
cow,  and  when  it  has  been 
standing,  is  not  in  a  condition 
to  sample  until  it  has  been 
thoroughly  mixed,  either  by 
pouring  from  one  pail  to  an- 
other, or  by  stirring  with  a 
long-handled  dipper.  Two 
ounces  of  the  well  mixed  milk ,  a. 
and  even  less,  put  into  a  con- 
venient wide-mouth  bottle  is 
a  sufl5cient  quantity  to  serve 
as  a  sample. 

The  milk  should  not  be 
measured  into  the  test-bottles 
until  it  has  cooled  to  70''  F. 
At  a  higher  temperature  the 
milk  is  expanded  and  may 
contain  an  abnormal  amount 
of  dissolved  air. 

When  the  milk  has  been 
standing  some  time  in  the 
sample  bottles,  it  is  necessary 
to  mix  it.  Pour  the  milk  from 
the  bottles  down  the  sides  of 
another  bottle  or  dish  and  not 
in  the  center  of  the  vessel. 
This  prevents  the  formation  of  foam  and  insures  the 
thorough  mixing  of  all  particles  of  cream. 


Fig.  4. 


1 6  THE    CHEMISTRY   OF   DAIRYING. 

14.  Measuring  the  Milk. — The  apparatus  used  for 
measuring  the  milk  is  called  a  pipette  (see  Fig.  4).  In 
order  to  fill  the  pipette  put  the  pointed  end  into  the 
milk,  apply  suction  with  the  mouth  until  the  milk  rises 
above  the  point  a  on  the  stem  ;  then  close  the  end  with 
the  index  finger  of  the  right  hand,  holding  the  pipette 
in  the  way  shown  in  the  cut.  The  second  and  third  fin- 
gers are  opposite  the  thumb,  while  the  little  finger  rests 
against  the  stem.  When  held  in  this  way  the  pipette  is 
prevented  by  the  little  finger  from  swaying  sidewise, 
while  the  firm  grasp  by  the  thumb  with  the  second  and 
third  fingers  on  the  opposite  sides  secures  a  good  hold 
and  leaves  the  index  finger  free  to  properly  control  the 
flow  from  the  pipette  and  to  make  rapid  measurements. 
If  the  pipette  is  wet,  rinse  it  with  a  little  of  the  milk  be- 
fore using  it  ;  remove  the  last  few  drops  by  blowing.  In 
passing  from  one  milk  to  another,  clean  the  pipette  by 
rinsing  it  with  a  little  of  the  milk  that  is  to  be  tested. 
Be  sure  to  give  the  pipette  a  thorough  cleaning,  first 
with  cold  water,  then  with  hot  water  at  the  close  of  the 
work. 

The  pipette  holds  17.6  cc.  of  water,  and  delivers 
eighteen  grams  of  milk.  When  the  milk  is  delivered 
into  the  test-bottles,  hold  the  test-bottle  in  the  left  hand 
at  an  angle  of  about  60°.  Allow  the  tip  of  the  pipette 
to  just  touch  one  side  of  the  neck  of  the  test-bottle. 
This  is  necessary  in  order  to  allow  air  to  pass  out  of  the 
test-bottle,  otherwise  the  milk  will  spatter  when  it  is 
delivered.     Allow  plenty  of  time  for  the  pipette  to  drain. 

15.  flaking  the  Test.— The   test-bottle  is  shown   in 


MAKING  THK   TKST. 


17 


•  J7.6  , 


Fig.  5,  and  is  provided  with  a  neck  which  has  a  graduated 
scale  from  i  to  10.  Each  larger  division  is  in  turn 
divided  into  five  smaller  divisions.  Each  test-bottle  is 
usually  provided  with  a  copper  collar  bearing  a  number. 
Fill  the  acid  measure,  Fig.  6,  up  to  the  17.6  cc.  mark, 
with  sulphuric  acid.  More  will  be  said  about  the  sul- 
phuric acid  in  another  para- 
graph. Pour  the  sulphuric 
acid  from  the  acid  measure 
into  the  test-bottle  which  con- 
tains the  milk. 

When  the  acid  is  poured  in, 
rotate  the   test-bottle  so  as  to 
wash  all  of  the  milk  down  from 
the  stem.      After  the  acid  is 
added,  take  hold  of  the  stem 
of  the  test-bottle,  and  mix  the 
acid    and    milk    by  rotating. 
The  solution  takes  on  a  dark 
coffee  color,  due  to  the  acid 
charring  the  sugar.    The  acid 
first  precipitates  the  casein  and         ^^s-  6. 
then  dissolves  it.     The  acid  does  not  act  on 
the  fat. 

The  fat  is  separated  from  the  milk  serum  by  centrif- 
ugal action.  There  are  a  number  of  different  makes 
and  sizes  of  centrifugal  machines  on  the  market,  but 
they  all  act  on  the  same  principle.  The  test-bottles  are 
placed  into  the  pockets  of  the  centrifugal  machine.  In 
case  there  are  not  enough  bottles  to  fill  the  machine, 


Fig.  5 


i8 


THE    CHEMISTRY   OF   DAIRYING. 


arrange  the  bottles  so  that  there  will  be  an  even  number 
on  each  side.  If  this  is  not  done  the  machine  is  unbal- 
anced, and  the  bearings  will  soor  become  badly  worn. 
The  bottles  are  to  be  whirled  five  minutes  at  the  rate  of 

900  revolutions  per  minute. 
Directions  for  speeding  the 
machine  will  be  found  in 
another  paragraph.  The 
starting  and  stopping  of 
the  machine  should  be  done 
graduall3^ 

After  whirling  five  min- 
utes the  test-bottles  are 
filled  with  hot  water  up  to 
about  the  eight  mark  on 
the  stem.  The  air  bubbles 
which  are  sometimes 
caught  in  the  neck,  should 
be  allowed  to  escape.  The 
bottles  are  then  whirled  two  minutes  in  order  to  collect 
all  of  the  fat  in  the  graduated  stem.  In  using  the  ma- 
chine always  close  the  cover  so  as  to  prevent  any  acci- 
dent. 

None  of  the  apparatus  used  in  this  test  is  patented, 
and  a  good  home-made  centrifugal  machine  will  answer 
every  purpose.  The  bottles  and  all  of  the  glassware  can 
be  purchased  separately. 

16.  Reading  the  Fat. — When  the  test  is  completed, 
the  fat  in  the  stem  presents  the  appearance  shown  in 
Fig.  7.     Read  from  the  lowest  point   b  to  the  highest 


READING   THE    FAT.  I9 

point  a.  Each  large  division,  as  i  to  2,  represents  a 
whole  per  cent,  of  fat.  Bach  of  the  smaller  divisions  is 
one-fifth  or  two-tenths  of  a  per  cent.  Suppose  the  top 
register  seven  large  and  one  small  divisions,  then  ^=7.2 
per  cent.  If  b  register  two  large  and  three  small  divi- 
sions, b  =  2.6.  7.2  —  2.6  =  4.6,  the  per  cent,  fat  in  the 
milk. 

Do  not  read  from  any  other  points  except  a  and  b, 
otherwise  the  results  will  be  too  low.  The  bottles  are 
made  to  read  in  just  this  way.  The  reading  should  be 
done  before  the  fat  cools,  and  streaks  down  the  sides. 
In  case  a  number  of  readings  are  to  be  made,  the  test 
bottles  should  be  set  into  a  pan  of  hot  water,  or  hot 
water  can  be  run  into  the  pan  of  the  machine,  so  as  to 
prevent  the  bottles  from  cooling.  A  pair  of  sharp 
pointed  dividers  can  be  used  in  the  way  indicated  in  the 
figure.    (See  Fig.  7.) 

All  test-bottles  should  be  rejected  when  the  inaccuracy  of 
the  divisions  can  be  detected  with  the  eye.  In  the  most 
careful  work  they  should  be  calibrated  with  mercury. 
Bach  small  division  is  equal  to  about  0.04  cc. ,  or  as  usually 
made,  one  and  one-half  millimeters.  For  ordinary 
work  the  bottles  can  all  be  tested  with  one  sample 
of  milk,  and  all  bottles  rejected  that  show  a  greater  dif- 
ference than  one  small  division.  Accurately  graduated 
test-bottles  can  usually  be  obtained  from  supply  houses 
that  deal  in  chemicals  and  glassware.  Other  pieces  of 
apparatus  can  be  obtained  from  the  same  sources.  Poor 
test-bottles  are  frequently  the  cause  of  much  trouble  and 
divSsatisf action  in  the  factory. 


20  THE    CHEMISTRY   OF   DAIRYING. 

17.  Speeding  the  flachine.— Count  the  number  of 
revolutions  that  the  test-bottles  make  for  every  revolu- 
tion of  the  crank  wheel.  Suppose  the  test-bottles  make 
twelve  revolutions  while  the  crank  makes  one.  In  order 
that  the  bottles  may  make  900  revolutions  in  a  minute, 
the  crank  must  be  turned  seventy-five  times  in  a  minute. 
(900-^12  =  75).  In  case  the  machine  is  more  than 
fifteen  inches  in  diameter  a  greater  number  of  revolu- 
tions is  necessary. 

18.  Centrifugal  Action. — As  previously  stated,  the 
fats  are  lighter  than  the  milk  serum,  and  when  the  milk 
is  whirled  in  the  test-bottles,  there  is  a  separation  of 
milk  fats  (lighter  particles),  from  the  milk  serum 
(heavier  portions).  The  serum  goes  to  the  outside  of 
the  circle  of  revolution,  while  the  fats  will  mass  in  the 
center  where  they  are  finally  collected  in  the  graduated 
stem.  The  sulphuric  acid,  which  is  one  and  eight-tenths 
heavier  than  water,  also  aids  in  the  separation  both  by 
increasing  the  specific  gravit}^  of  the  milk  serum  and  by 
its  chemical  action  upon  the  albumin  and  casein.  The 
cream  separator  also  works  on  this  same  principle. 
Centrifugal  action  is  well  illustrated  by  whirlpools, 
where  all  of  the  foam  and  light  materials,  as  leaves,  col- 
lect at  the  center.  In  the  case  of  the  separator,  pro- 
vision is  made  for  the  escape  of  the  fat  into  a  tube  as  it 
collects  at  the  center. 

19.  The  Acid. — Commercial  sulphuric  acid  (sp.  gr. 
1.82),  about  ninety  per  cent,  strength,  can  usually  be 
obtained]  for  two  and  one- half  cents  per  pound  when 
purchased  in  carboy  lots  ;   one  pound  of  acid  will  make 


THE   ACID. 


21 


about  twenty  tests.  When  the  acid  is  too  strong,  the  fat 
presents  a  blackened  and  charred  appearance,  if  too 
weak,  particles  of  un- 
dissolved casein  ap- 
pear immediately  be- 
low the  fat  line.  When 
just  right,  the  fat  sep- 
arates in  a  distinct  and 
well  defined  layer,  and 
looks  like  butter.  The 
acid  as  well  as  the 
washings  and  contents 
of  the  test-bottles  can 
be  handled  only  in 
glass  or  earthenware. 
The  acid  should  never 
come  in  contact  with 
a  tin  or  metallic  dish 
of  any  kind.  If  any 
acid  is  spilled  on  the 
floor  or  desks,  wash 
it  up  immediately, 
using  plenty  of  water. 
If  a  large  quantity  is 
spilled,  absorb  it  with 
sawdust,  bran,  or  fine 
clay.  In  case  any  is 
spilled  on  the  cloth- 
ing rinse  with  water 
and  then  apply  ammonia  to  the  spots.     Never  throw  the 


22  THE    CHEMISTRY    OF    DAIRYING. 

acid  waste  near  a  tree  or  where  a  person  or  animal  is 
obliged  to  walk. 

A  convenient  form  of  apparatus  for  measuring  the 
acid  is  shown  in  Fig.  8.  a  is  the  acid  bottle  connected 
with  glass  tube  dd  to  a  loo  cc.  pipette  cc.  The  stopcock 
/can  be  turned  so  as  to  allow  the  acid  to  run  into  the 
test-bottle  g.  The  automatic  pipette  is  fastened  to  an 
iron  stand  dd,  which  rests  upon  the  table.  Other  forms 
of  apparatus  are  also  in  use,  but  in  ordinar}^  practice  a 
good  strong  glass  vessel  with  a  good  lip  for  pouring  is  the 
cheapest  and  best  arrangement  for  the  acid.  A  white 
tile  is  excellent  to  have  on  the  table  under  the  acid  bottle. 

20.  Composite  Test. — In  actual  creamerj^  practice  the 
daily  testing  of  each  patron's  milk,  or  in  the  dair}^,  the 
testing  of  both  morning's  and  evening's  milk  from  each 
cow,  is  too  expensive  and  consumes  too  much  time.  To 
obviate  this  daily  testing,  a  composite  or  compound 
sample  is  made  up  by  saving  a  little  of  the  milk  from 
each  milking,  in  a  pint  fruit  can.  At  the  end  of  the  week 
or  two  weeks  the  compound  sample  is  carefully  mixed 
and  tested.  Inasmuch  as  this  test  represents  a  propor- 
tional part  of  each  lot  of  milk,  it  gives  the  average 
amount  of  fat  in  the  milk  for  that  period.  In  creameries 
and  factories  where  milk  is  paid  for  b}^  test,  the  compos- 
ite test,  when  properly  carried  out,  gives  good  results. 

The  composite  sample  should  be  kept  covered  so 
that  the  surface  of  the  cream  will  not  become  dry  and 
leathery.  The  sample  should  also  be  kept  in  a  cool 
place  to  prevent  fermentation.  Various  chemicals  are 
used  to  keep  the  milk  fresh. 


COMPOSITE   TEST.  23 

Potassium  bichromate  has  been  found  to  give  the 
best  satisfaction.  About  as  much  potassium  bichromate 
as  will  la3^  on  the  end  of  a  pen  knife  blade  will  be  a 
sufficient  amount  to  use  in  each  sample  can.  Put  in  the 
bichromate  when  the  sample  cans  are  empty,  then  no 
more  need  be  added  until  a  new  composite  sample  is 
started.  It  imparts  its  characteristic  yellow  color  to  the 
milk. 

In  case  corrosive  sublimate  or  any  poisonous  material 
is  used  in  the  composite  sample,  it  is  best  to  color  the 
milk  with  aniline  so  as  to  prevent  the  milk  from  being 
used,  and  accidental  poisoning  resulting  therefrom. 

Small  four  or  six  ounce  wide-mouth  bottles  may 
be  used  for  holding  the  compositive  samples.  Bottles 
with  glass  stoppers  are  the  best.  Rubber  stoppers  may 
be  used  but  cork  stoppers  should  never  be  used.  They 
are  difficult  to  clean  and  they  cause  the  milk  to  sour. 
When  the  composite  sample  becomes  "  lumpy"  and  is 
difficult  to  sample,  a  very  small  piece  of  caustic  potash 
may  be  added  before  mixing  the  milk.  The  potash  will 
dissolve  the  lumps.  A  few  drops  more  than  17.6  cc.  of 
acid  should  then  be  u^Ded. 

When  there  are  only  a  small  number  of  cows,  the  fol- 
lowing plan  may  by  followed  :  Save  about  two  ounces  of 
each  cow's  milk  separately  in  glass  bottles  or  cans ;  at 
the  next  milking  add  the  same  quantity  or  a  propor- 
tional quantity.  A  composite  sample  of  the  day's  milk 
is  thus  obtained,  and  while  still  fresh  is  mixed  and  then 
by  means  of  a  small  pipette,  5.9  cc.  are  measured  into 
a  test-bottle  twice  the  size  of  those  ordinarily  used,  or 


24 


THE    CHEMISTRY   OF    DAIRYING. 


test-bottles  made  for  thirty-five  cc.  of  milk.  The  milk 
of  six  days  can  then  be  measured  directly  into  the  test- 
bottles,  and  then  tested.  The  milk  is 
measured  while  sweet  and  fresh  and  will 
not  harm  if  it  sours  in  the  test-bottles. 
No  preservatives  need  be  used.  The  milk 
sample  of  four  ounces  can  then  be  saved 
and  there  is  no  loss  through  the  taking 
of  large  samples. 

In  testing  skim  milk,  the  special  bot- 
tles, with  the  small  neck  and  the  side  tube 
for  the  addition  of  the  acid,  should  be 
used.  It  must  be  remembered  that  even 
the  small  amount  of  fat  that  is  obtained 
in  the  neck  is  not  necessarily  all  of  the 
fat  in  the  skim-milk  because  some  of  it 
may  be  present  in  such  a  fine  state  of  divi- 
sion that  it  is  not  brought  up  into  the 
neck.  This,  however,  does  not  seriously 
impair  the  test.  When  the  test  shows 
only  a  trace  of  fat,  the  butter-maker  can  feel  satisfied  that 
he  is  doing  good  work. 

21.  Frozen  Milk. — When  a  can  of  milk  freezes  the 
ice  forms  on  the  outside  and  there  is  a  central  part  that 
does  not  freeze.  The  unfrozen  part  is  richer  in  fat  and 
solids  than  the  frozen  part.  The  ice  in  the  center  of  the 
can  is  also  richer  in  milk  solids  than  the  ice  of  the  outer 
portions.  When  frozen  or  partially  frozen,  milk  is  not 
in  a  condition  to  sample. 


PROrERTT  UUbUir 


25 

REFERENCES  TO  CHAPTER  II. 

1.  The  Babcock  Test.  A  New  Method  for  the  Estimation  of 
Fat  in  Milk,  Especially  Adapted  to  Creameries  and  Cheese  Fac- 
tories. Wisconsin  Experiment  Station,  Bulletin  No.  24  ;  also 
Annual  Report,  1890. 

2.  Babcock  Test.  Notes  on  Its  Use  and  the  I^actometer.  Wis- 
consin Experiment  Station,  Bulletin  No.  31. 

3.  Application  of  Dr.  Babcock's  Centrifugal  Method  to  the 
Analysis  of  Milk,  Skim-milk,  Etc.  Cornell  University  Experi- 
ment Station,  Bulletin  No.  29. 

4.  New  Points  in  Manipulation  of  the  Babcock  Test.  Illinois 
Experiment  Station,  Bulletin  No.  27. 

5.  The  Babcock  Test.  Association  of  Official  Agricultural 
Chemist  Report,  1890. 

6.  The  Babcock  Method  of  Finding  the  Amount  of  Butter-Fat 
in  Milk.  Connecticut  State  Experiment  Station,  Bulletin  No. 
106;  also  Reports,  1891,  1894. 

7.  Directions  for  Using  the  Babcock  Milk  Test.  Pennsylvania 
Experiment  Station,  Bulletin  No.  33,  Report,  1895. 

8.  The  Babcock  Method  of  Milk  Analysis.  F.  T.  Shut: 
Analyst,  17,  200;  Chemical  News,  64,  4. 

9.  Accuracy  of  the  Babcock  Milk  Test.  Cornell  University 
Experiment  Station,  Bulletin  No.  25. 

10.  Accuracy  of  the  Babcock  Milk  Test.  Illinois  Experiment 
Station,  Bulletin  No.  14. 

11.  Comparative  Trials  of  the  Babcock  Milk  Test.  Heinrich  : 
Molkerei  Zeitung,  1893,  No.  4. 

12.  The  Babcock  Test.  Wiley  :  Agricultural  Analysis,  Vol.  III. 

13.  Marking  Test-Bottles.  Illinois  Agricultural  Experiment 
Station,  Bulletin  No.  18. 

14.  Milk  Sampling.  Delaware  Experiment  Station,  Bulletin 
No.  31. 

15.  The  Testing  of  Milk.  North  Carolina  Experiment  Sta- 
tion, Bulletin  No.  113. 

16.  Composite  Milk  Samples.  Patrick  :  Journal  of  Analytical 
and  Applied  Chemistry,  5,  8. 


26  THE    CHEMISTRY    OF    DAIRYING. 

17.  The   Composite    Test.      Wisconsin    Experiment    Station, 
Bulletin  No.  36. 

18.  Composite  Sampling  of  Milk.     Iowa  Experiment  Station, 
Bulletins  Nos.  9,  14  and  22. 

19.  Composite  Method  of  Milk   Sampling.      Illinois  Experi- 
ment Station,  Bulletins  Nos.  16  and  18. 

20.  Method  of   Sampling  Milk  for  Analysis.      Penns3'lvania 
Experiment  Station,  Annual  Report,  1892. 

21.  Preservatives  for  Milk  Samples.     Iowa  Experiment  Sta- 
tion, Bulletin  No.  11. 

22.  Scovell's  Milk  Sampler.     Wiley:    Agricultural  Analysis, 
Vol.  III. 


CHAPTER  III. 
Milk  Fats. 

The  fat  which  is  present  in  milk  is  not  a  single  chem- 
ical compound,  but  is  a  mixture  of  various  separate  fats, 
all  intimatel}^  mixed  together.  Each  separate  fat  has  its 
own  name  and  special  characteristics.  Each  fat,  when 
finally  separated  into  the  materials  of  which  it  is  com- 
posed, shows  the  presence  of  only  three  elments,  or 
building  materials :  Carbon,  hydrogen  and  oxygen. 
The  various  fats  differ  from  each  other,  chemically,  in 
two  w^ays  :  ( i )  In  the  proportion  in  which  these  elements 
or  building  materials  are  present,  as  one  fat  may  contain 
more  or  less  carbon  than  another  ;  and  (2)  the  way  in 
which  these  elements  are  united,  just  as  a  pile  of 
bricks  may  be  put  together  in  a  number  of  different 
ways.  The  fact  that  the  butter-fat  is  composed  of  vari- 
ous separate  fats,  shows  itself  in  various  ways.  At  cer- 
tain seasons  of  the  year  the  butter  is  naturally  harder,  at 
other  times  it  is  softer ;  then  again  the  butter  from  some 
cows  is  hard  and  firm,  while  from  other  cows,  even  upon 
the  same  food,  it  is  naturally  soft  and  salve-like. 
Chemical  analysis  has  shown  that  this  is  due  to  the  dif- 
ference in  the  proportions  in  which  the  various  fats  are 
present.  The  quality  of  the  butter,  as  hard  or  soft,  is 
influenced  by  the  quality  of  the  separate  fats  which  com- 
pose the  butter.  The  different  fats  present  in  milk,  ac- 
cording to  Blyth,  are  : 


28  THE    CHEMISTRY    OF    DAIRYING. 

Per  cent, 
of  butter. 

1.  Palmitin  \  ^ 

2.  Stearin     j    5° 

3.  Olein 40 

4.  Butyrin 7 

5.  Caproin,  caprylin  and  others 3 

22.  Palmitin  is  a  white  solid  fat  found  in  butter  and  also 
obtained  from  palm  oil,  and  other  sources.  Human  fat 
is  ver}^  rich  in  palmitin.  When  chemicall}'  pure  it  is 
tasteless.  Palmitin  forms  crystals  like  snow  flakes.  This 
fat  has  a  high  melting-point,  145.4°  F. 

23.  Stearin  is  a  white  solid  fat  like  palmitin  and 
has  a  high  melting-point,  157°  F.  It  also  crystallizes  in 
the  same  way  as  palmitin.  For  a  long  time  these  two 
fats,  palmitin  and  stearin,  were  thought  to  be  one  fat,  to 
which  was  given  the  name  margarine.  Among  the  fats 
that  are  particularl}^  rich  in  stearin  are  beef  and  mutton 
tallow.  These  substances  melt  at  a  much  higher  point 
than  butter,  and  they  are  the  materials  used  in  the  adul- 
teration of  butter,  forming  the  product  known  as  oleo- 
margarine, which  is  a  mechanical  mixture  of  the  fats 
palmitin  and  stearin  (margarine)  with  olein.  The 
larger  the  proportion  of  either  stearin  or  palmitin  in  any 
fat,  the  higher  its  melting-point.  '  When  one  butter  has 
a  higher  melting-point  than  another,  it  is  due  to  the 
presence  of  a  larger  amount  of  palmitin  or  stearin. 
These  two  fats  make  up  about  half  of  the  w^eight  of  the 
milk  fats. 

24.  Olein  is  quite  different  from  either  palmitin  or 
stearin.     This  fat  makes  up  about  forty  per  cent,   of 

1  The  palmitin  and  stearin  also  include  the  myristic  acid  of  butter. 


GI.YCERINK   A   PART   OF    AI,I,   FATS.  29 

the  weight  of  butter.  At  medium  temperatures,  olein 
is  a  liquid  or  oil.  It  solidifies  at  a  temperature  of  40°  F. 
It  is  a  liquid  at  the  ordinary  temperature  of  the  cold 
deep  setting  of  milk,  that  is,  the  setting  of  milk  in 
ice  water.  Olein  has  the  property  of  readily  and 
copiously  dissolving  palmitin  and  stearin.  The  larger 
the  per  cent,  of  olein  in  a  butter  or  fat,  the  softer  it  is. 
Sperm  oil,  cod  liver  oil,  and  many  of  the  vegetable  oils 
are  rich  in  olein. 

25.  Butyrin,  the  fourth  fat  in  milk,  melts  at  a  tempera- 
ture of  77°  F.  ;  milk  fats  contain  from  six  to  seven  per 
cent,  of  butyrin.  Although  butyrin  forms  such  a  small 
proportion  of  milk  fat,  it  is  the  characteristic  fat  of  but- 
ter. It  is  the  butyrin  which  gives  to  butter  its  individ- 
uality, and  its  presence  or  absence  is  the  distinguishing 
point  between  butter  and  oleomargarine.  Butyrin,  when 
decomposed,  forms  butyric  acid.  In  rancid  and  stale 
butter,  the  rank  odor  is  due  to  butyric  acid. 

26.  Caproin  and  Caprylin  comprise  only  a  small  part 
of  the  fats  of  milk,  and  they  do  not  require  any  special 
consideration. 

27.  Glycerine  a  Part  of  all  Fats. — All  fats  have  one 
point  in  common  :  when  they  are  broken  up  into  simpler 
products,  glycerine  is  one  of  the  products  always  formed  ; 
the  other  product  is  an  acid  with  an"  ic"  ending  in 
place  of  the  "in"  ending  of  the  fat.  By  the  action  of 
superheated  steam, 

Palmitin  yields  palmitic  acid  and  glycerine. 
Olein  "      oleic  "       "  " 


30  THE    CHEMISTRY    OF    DAIRYING. 

Stearin  j'ields  stearic  acid  and  ghxerine. 
Butyrin      "      butyric      "       *'  " 

Caproin      "      caproic      "      "  " 

Caprylin     **      caprylic     "      " 

Milk  fats  are  frequentl}^  defined  as  glycerides  of  the 
fatty  acids.  Thej^  are  neutral  bodies.  All  of  the  fats 
are  lighter  than  water.  The  mixed  butter-fats  are  in- 
soluble in  water ;  all  are  soluble  in  ether,  chloroform, 
gasoline,  and  other  similar  solvents.  Butyrin,  caproin, 
and  capr^'lin,  when  exposed  to  the  air  and  light  for  anj^ 
length  of  time  undergo  decided  changes  in  composition, 
which  finally  result  in  the  production  of  the  corres- 
ponding fatt}^  acids,  and  the  product  is  rancid  butter. 
Milk  fats  compared  with  starch  contain  but  little  oxy- 
gen in  their  composition.  When  the  fats  are  acted  upon 
by  the  air  and  some  chemicals,  they  are  oxidized.  The 
dr3'ing  of  paint  is  an  oxidation  of  some  of  the  fats. 

28.  Food  Value  of  Fats. — Fat  is  a  very  concentrated 
form  of  heat-producing  food,  because  it  contains  such  a 
large  amount  of  carbon.  In  very  small  seeds,  like  flax, 
the  fat  is  one  of  the  main  reserve  forms  of  food.  One 
pound  of  fat  when  burned  wnll  produce  about  tw^o  and 
one-fourth  times  more  heat  than  a  pound  of  starch. 
Starch  contains  forty-four  per  cent,  carbon,  and  fat 
contains  sevent3-six  per  cent,  carbon. 

29.  Saponification  and  Other  Properties  of  Fats. — 
When  certain  chemicals  known  as  alkalies,  such  as  potash 
and  soda,  are  heated  with  the  fats  they  form  soaps;  the 
process  is  called  saponification.     When  saponification 


SAPONIFICATION  AND  OTHKR  PROPERTIES  OP  PAT.  3 1 

takes  place,  part  of  the  alkali  unites  with  the  fatty  acid 
of  the  fat  and  forms  soap,  while  the  glycerine  part  of 
the  fat  unites  with  the  remainder  of  the  alkali  and  forms 
glycerine.     Fat  +  alkali  =  soap  +  glycerine. 

Butter-fats  have  a  less  power  of  taking  up  iodine  than 
the  fats  which  are  used  for  making  oleomargarine.  But- 
ter has  an  iodine  number  of  about  thirty,  while  that  of 
oleomargarine  is  forty-five  to  fifty. 

The  main  differences  in  composition  between  butter 
and  oleomargarine  is  illustrated  in  the  following  table : 

Butter.  Oleomargarine. 

Butyric  acid,  etc 4.50  per  cent.  0.25  per  cent. 

Iodine   number' 30  45 

Melting  point 85  to  95°  98  to  100° 

Insoluble  fatty  acids 88.5  per  cent.    90  to  95  per  cent. 

Simple  methods  for  detecting  adulterated  butter  will 
be  given  in  another  part  of  the  work. 


REFERENCES  TO  CHAPTER  III. 

1.  Constitution  of  Butter-Fat.      Allen  :    Commercial  Organic 
Analysis. 

2.  The  Fat  of  Butter.     Hehner  and  Angel :  Butter,  Its  Analy- 
sis and  Adulteration. 

3.  The  Composition  of  Butter-Fat.     I^adenburg :    Handwoer- 
terbuch  der  Chemie,  Vol.  II. 

4.  Chevreul  :    Recherches     chemiques     sur     les    corps     gras 
d'origine  animale. 

5.  Butter-Fat.     Schrodt  and  Henzold  :    Landwirtschaftlichen 
Versuchs-Stationen,  1892,  40,  229. 

6.  Composition  of  Butter-Fat.     Blyth  :  Foods,    their  Composi- 
tion and  Analysis. 

7.  TheSpecificGravityof  Butter-Fat,  Etc.    Benedikt :  Analyse 
der  Fette  und  Wachsarten. 


32  THE    CHEMISTRY    OF    DAIRYING. 

8.  Abnormal  Butter  [Fat].     Morse  :  Journal  of  Analytical  and 
Applied  Chemistry,  7,  No.  i. 

9.  The  Fatty  Acids  in  Butter.     Heintz  :  Zeitschrift  fiir  analy- 
tische  Chemie,  17. 

10.  The  Butyric  Acid  from  Milk  Fat.     Grunzweig  :  Annalen 
der  Chemie,  158,  117. 

11.  Butyric  Acid.     Remsen  :  Organic  Chemistry. 

12.  The  Insoluble  Fatty  Acids.     Kottstorffer :  Zeitschrift  fiir 
analytische  Chemie,  18. 

13.  The  Iodine  Absorption  of  Fats.     Hiibel  :    Journal    of    the 
Society  of  Chemical  Industry,  1884,  65. 

14.  The  Characteristics  of  Butter  and  Other  Fats.     Benedikt : 
Analyse  der  Fette  und  Wachsarten. 

15.  The  Melting-Point  of  Butter  and  Other  Fats.    Bensemann ; 
Zeitschrift  fur  analytische  Chemie,  1886,  197. 

16.  The  Saponification  of  Fats.     Richter  :  Organic  Chemistry. 

17.  The  Glycerol  Content  of  Fats.     Benedikt  and  Zsigmondy  : 
Chemiker-Zeitung,  9,  975. 


CHAPTER  IV. 
Milk  Sugar  and  Lactic  Acid. 

30.  Physical  Properties. — When  milk  sugar  is  obtained 
from  milk  and  is  in  a  pure  state,  it  is  in  appearance,  quite 
like  ordinary  confectionary  sugar,  but  it  does  not  possess 
any  marked  sweet  taste.  It  is  not  as  easily  soluble  in 
water  as  cane  sugar.  Ordinary  sugar  dissolves  in  less  than 
a  third  of  its  own  weight  of  cold  water,  while  milk  sugar 
requires  six  times  its  own  weight  of  cold  water  for  solu- 
tion. Milk  sugar  is  not  as  heavy  as  ordinary  sugar;  its 
specific  gravity  is  1.53,  while  that  of  cane  sugar  is  1.60. 
Milk  sugar  takes  a  very  important  part  in  butter-  and  cheese- 
making. 

31.  Fermentation  of  flilk  Sugar. — Under  favorable 
circumstances,  milk  sugar  undergoes  fermentation.  In 
milk,  one  kind  of  fermentation  is  brought  about  by  the 
action  of  minute  organisms  known  as  the  lactic  acid 
ferments.  These  organisms  may  be  considered  as  micro- 
scopic vegetable  bodies.  These  minute  plant-like  bodies 
live,  develop  and  die  in  milk,  just  as  any  higher  plant  de- 
velops in  the  soil.  Milk  is  a  perfect  food  for  the  develop- 
ment of  the  lactic  acid  organisms.  It  contains  a  substance, 
milk  sugar,  capable  of  undergoing  fermentation.  The 
necessary  amount  of  water  for  fermentation  is  also  pres- 
ent, and  as  soon  as  the  "  vSpores"  or  seeds  of  the  lactic 
acid  organisms  find  their  way  into  the  milk,  and  the 
proper  temperature  is  reached,  fermentation  takes  place. 


34  'I'HK    CHEMISTRY   OF    DAIRYING. 

In  winter,  milk  keeps  sweet  much  longer  than  in  sum- 
mer. This  is  because  the  ferment  does  not  develop  at 
a  low  temperature. 

A  temperature  of  70°  to  90°  F.  is  the  most  favorable 
for  its  growth.  Below  zero  and  above  the  boiling  point 
of  water,  the  ferment  is  killed.  Not  only  milk  but  all 
of  its  products  which  contain  a  small  amount  of  milk 
sugar,  as  cream,  cheese,  and  even  butter  are  capable  of 
undergoing  the  lactic  acid  fermentation  to  a  greater  or 
less  extent. 

32.  Chemistry  of  the  Process. — When  milk  sours,  the 
milk  sugar  is  partially  converted  into  lactic  acid  by  the 
lactic  acid  ferment.  The  acid  has  a  very  sour  taste. 
The  chemical  name  of  milk  sugar  is  lactose.  When  the 
ferment  begins  to  act,  lactose  is  split  up  into  two  bodies, 
galactose  and  dextrose.  The  galactose  that  is  formed  is 
still  farther  acted  upon  by  the  ferment  and  forms  two 
parts  of  lactic  acid. 

Lactose,  (milk  sugar)  forms  galactose  and  dextrose. 
C,,U,,On,B.,0  =  CeHi^Oe  +  CeHi.Oe 

Galactose  forms  two  parts  of  lactic  acid 
C6Hi.,06  =  2C3H603. 

The  dextrose  part  may  undergo  a  similar  change. 
Hence,  one  part  of  milk  sugar,  when  fermented,  is  finally 
split  up  and  produces  two  or  four  parts  of  lactic  acid. 
When  the  lactic  acid  is  formed  from  the  milk  sugar,  the 
milk  changes  from  sweet  to  sour,  and  finally  when  the 
acid  reaches  a  certain  point  the  milk  curdles  ;  that  is, 
the  casein  is  coagulated.  When  milk  is  boiled  and  then 
curdles,  it  shows  the  presence  of  four-tenths  per  cent. 


THE   CUI.TURE   OR   STARTER.  35 

of  lactic  acid.  The  fermentation  can  take  place  only 
up  to  a  certain  point ;  it  then  stops  and  the  action  can- 
not go  beyond  this  point,  because  the  acid  that  is  de- 
veloped kills  the  ferments.  Very  frequently  ferments 
are  killed  by  their  own  products,  just  as  an  animal 
would  be  killed  by  the  products  of  respiration  if  shut  in 
a  closed  room. 

33.  The  Ripening  of  Cream.— The  ripening  of  cream 
is  due  mainly  to  the  action  of  the  lactic  acid  ferments. 
In  the  creamery,  the  process  is  hastened  by  warming  the 
cream  in  vats,  and  holding  it  at  a  temperature  of  about 
70°  F.,  until  the  process  is  completed,  and  then  cooling 
and  churning  the  cream.  In  addition  to  the  lactic  acid 
organisms,  other  organisms  may  find  their  way  into  the 
milk  or  cream  and  produce  undesirable  products  which 
render  the  cream  bitter,  and  cause  foul  butter.  In  the 
ripening  and  handling  of  cream  the  most  scrupulous 
cleanliness  is  necessary  so  as  to  prevent  the  action  of  the 
undesirable  ferments,  and  to  permit  of  the  action  of  the 
desirable  ones.  Various  attempts  have  been  made  to 
use  pure  cultures  (seeds)  of  the  lactic  acid  and  other 
organisms  for  the  ripening  of  the  cream.  It  is  believed 
by  many  that  great  improvements  will  be  made  in  the 
ripening  of  cream. 

34.  The  Culture  or  Starter.— In  ripening  cream  the 
process  is  frequently  hastened  by  adding  a  starter.  A 
starter,  or  more  properly  culture,  is  a  little  sour  skim  milk 
that  contains  the  spores  (seeds)  of  the  lactic  acid  ferment. 
When  these  spores  are  introduced  into  the  cream,  they 


36 


THK    CHEMISTRY   OF   DAIRYING. 


rapidly  multiply  and  produce  the  desired  effect.  The 
action  is  checked,  when  the  proper  point  is  reached,  by 
cooling  the  cream  and  churning  it.  In  the  selection  of 
the  starter,  much  care  should  be  exercised  ;  take  the 
milk  from  a  fresh  and  perfectly  healthy  cow  so  as  to  get 
a  pure  culture,  which  is  as  necessary  as  is  good  yeast 
for  bread-making. 

35.  Determining  the  Acid  in  Mill^. — For  this  work  a 
burette  (see  Fig.  lo)  will  be 
necessary,  also  a  standard  alkali 
solution  and  an  indicator.  Meas- 
ure out  twenty-five  cc.  of  milk 
into  a  glass  dish,  add  three  to 
five  drops  of  indicator  (phenol- 
phthalein) .  The  milk  or  cream 
may  then  be  diluted  with  75  or 
100  cc.  of  water.  Add  the  stand- 
dard  alkali  (tester)  from  a  bu- 
rette, until  the  color  of  the  milk  is 
changed  to  a  faint  reddish  purple 
tinge.  At  this  point  sufficient  al- 
kali has  been  added  to  neutralize 
all  the  free  acid  of  the  milk.  The 
standard  alkali  solution  is  some- 
times spoken  of  as  the  tester  so- 
lution. 

The  amount  of  alkali  used  will  depend  upon  the 
amount  of  free  acid  in  the  milk.  For  ripened  cream 
butter  twenty-two  cc.  of  alkali  should  neutralize  the 
acid  in  twenty-five  cc.  of  the  cream.     In  making  the  test, 


Fig.  10. 


REFERENCES   TO   CHAPTER   IV.  37 

rain  water  should  be  used  for  rinsing  and  washing  the 
dishes,  as  strong  alkaline  waters  will  destroy  the  accuracy 
of  the  test.  The  alkali  can  be  prepared  only  by  a  druggist 
or  one  who  has  a  delicate  balance  at  hand.  It  is  made  by 
dissolving  five  and  six-tenths  grams  of  potassium  hy- 
droxide or  four  grams  of  sodium  hydroxide  per  liter  of 
distilled  water. 

Note  the  alkali  used  for  sweet  milk. 
"        "  "       "    sour       *' 

"       "    sweet  cream. 
"        "         '*       **    sour  cream. 

The  object  of  this  test  is  to  enable  the  butter-maker 
to  get  his  cream  in  about  the  same  conditions,  as  to 
ripeness,  from  day  to  day,  so  as  to  aid  in  the  production 
of  a  uniform  article  of  butter. 

Attempts  have  been  made  to  utilize  this  test  in  deter- 
mining the  ripeness  of  milk  for  cheese-making  purposes. 
The  test  will  show  the  acidity  of  the  milk  but  it  does  not 
necessarily  follow  that  the  acidity  and  the  physical  con- 
ditions of  the  casein,  favorable  for  coagulation  are  iden- 
tical. There  is  a  class  of  bacteria  which  curdle  milk 
without  rendering  it  acid ;  on  this  account,  the  alkali 
test  is  not  applicable  for  general  cheese-making  purpo- 
ses. The  test  is  of  value  in  the  manufacture  of  sweet 
curd  cheese,  to  determine  the  fitness  of  the  milk  for  use, 
as  to  whether  it  is  too  old  or  not,  because  the  older  the 
milk,  the  greater  is  the  amount  of  lactic  acid  present. 

REFERENCES  TO  CHAPTER  IV. 

1.  Milk  Sugar.     Remsen  :  Organic  Chemistry. 

2.  Ripening   Cream   with    Pure    Cultures.       Conn  :    (Storrs) 


38  THE    CHEMISTRY   OF    DAIRYING. 

Connecticut  Experiment  Station.     Sixth  and   Seventh  Annual 
Reports. 

3.  Ripening  of  Cream.  Conn:  (Storrs)  Connecticut  Experi- 
ment Station.     Third  Annual  Report. 

4.  Ripening  of  Cream  with  Artificial  Cultures.  Adametz  : 
Landwirtschaftlichen  Versuchs-Stationen,  1892. 

5.  Artificial  Butter  Cultures.     Storch  :  Milch  Zeitung,  1890. 

6.  Artificial  Butter  Cultures.  Weigmann:  Milch  Zeitung,  1890. 

7.  Bactesia  in  the  Dair)-.  Conn  :  (Storrs)  Connecticut  Exper- 
iment Station.  Fourth,  Fifth,  Sixth,  Seventh,  and  Eighth  An- 
nual Reports. 

8.  Milk  Fermentations.  United  States  Department  of  Agri- 
culture, Farmers'  Bulletin  No.  9. 

9.  The  Souring  of  Milk.  United  States  Department  of  Agri- 
culture, Farmers'  Bulletin  No.  29. 

10.  Dairy  Bacteriology.  United  States  Department  of  Ag- 
riculture, Office  of  Experiment  Stations,  Bulletin  No.  25. 

11.  The  Number  of  Bacteria  in  Milk.  (Storrs)  Connecticut 
Experiment  Station.     Seventh  Annual  Report. 

12.  Bacteria  in  Their  Relation  to  the  Dairy.  Ivugger  :  Min- 
nesota Experiment  Station.     Annual  Report,  1893. 

13.  Ripening  of  Cream,  and  Milk  Fermentations.  Article  in 
Handbook  of  Experiment  Station  Work. 

14.  The  Action  of  Different  Classes  of  Bacteria  on  Milk.  Ad- 
ametz.    Monatschrifte   fiir   Thierheilkunde,    1890. 

15.  Experiments  with  Cream :  Ripening,  Flavor,  Aroma, 
Acid.  Conn :  (Storrs)  Connecticut  Experiment  Station,  Bul- 
letin No.  16. 

16.  Experiments  in  the  Ripening  of  Cream  by  Means  of  Pure 
Cultures.  F.  Fries  and  H.  P.  Lunde:  Reported  in  Experiment 
Station  Record,  7,  No.  3. 

17.  Abnormal  Ripening  of  Cream  Due  to  Faulty  Character  of 
Milk.     L.  Adametz  :  Milch  Zeitung,  1893,  No.  18. 

18.  Different  Species  of  Bacteria  Producing  Lactic  Acid.  Conn: 
(Storrs)  Connecticut  Experiment  Station.  Third  Annual 
Report. 


REFERENCES  TO   CHAPTER   IV.  39 

19.  "Soapy"  Milk,  and  the  Sources  of  Bacteria  in  Milk.  Weig- 
mann  and  Zirn :  Milch  Zeitung,  23,  1893. 

20.  Cream  Ripening  with  Pure  Cultures.  Milch  Zeitung.  Ex- 
periment Station  Record,  7,  No.  i. 

21.  An  Acid  Test  of  Cream.  Illinois  Experiment  Station,  Bul- 
letin No.  32. 

22.  The  Alkaline  Tablet  Test  of  Acidity  in  Milk  or  Cream. 
Wisconsin  Experiment  Station,  Bulletin  No.  52. 

23.  Lactic  Acid  Ferments.  Pasteur  :  Studies  on  Fermenta- 
tion. 

24.  Outlines  of  Dairy  Bacteriology.     Russell. 

25.  Le  I^ait,  Etudis  Chemiques  et  Microbiologiques.  Duclaux. 

26.  Determining  the  Acid  in  Milk.  Hopkins  and  Powers. 
Report  Annual  Convention  of  the  Association  of  Ofl&cial  Agri- 
cultural Chemists,  1895. 


CHAPTER  V. 

The  Lactometer  and  the  Detection  of  Adulterated 

Milk. 

The  lactometer  is  a  piece  of  apparatus  used  to  deter- 
mine the  specific  gravity  of  milk  ;  that  is,  the  weight  of 
an  equal  volume  of  milk  compared  with  the  weight  of 
an  equal  volume  of  water  under  the  same  conditions. 

36.  Specific  Gravity  of  Milk.— The  fat  in  milk  is 
lighter  than  water;  it  has  a  specific  gravity  of  about 
0.93.  This  means  that  a  given  volume  of  fat  weighs 
0.93  as  much  as  the  same  bulk  of  w^ater,  when  under  the 
same  conditions  as  to  temperature,  etc.  The  ash,  milk 
sugar,  casein,  etc.,  all  have  a  higher  specific  gravity 
than  water  taken  as  i .  When  a  given  weight  of  sugar 
or  salt  is  dissolved  in  a  definite  amount  of  water,  the 
specific  gravity  of  the  solution  is  increased  proportionally 
to  the  amount  of  sugar  or  salt  that  is  added.  When  the 
fat  of  milk  is  removed,  the  specific  gravity  is  increased 
because  the  fat  has  a  specific  gravity  of  only  0.93,  while 
all  of  the  other  constituentS|  have  a  specific  gravity 
greater  than  i . 

If  there  were  but  one  ingredient  in  milk,  the  lactome- 
ter could  tell  how  much  there  was  of  that  ingredient,  but 
the  presence  of  more  than  one  constituent  complicates 
the  problem. 

The  richer  a  sample  in  casein,  milk  sugar  or  ash,  the 
greater  is  its  buoyant  power  ;    it  has  a  higher  specific 


EFFECT   OF   TEMPERATURE.  41 

gravity.  This  is  indicated  by  the  lactometer  stem  not 
sinking  to  so  great  a  depth  as  it  otherwise  would.  On 
the  other  hand,  the  richer  a  milk  in  fat  the  greater 
the  depth  to  which  the  spindle  will  sink.  There  is  a 
certain  point  between  these  two  opposing  powers  to 
which  the  spindle  will  sink  in  pure  milk.  Pure  milk 
has  a  specific  gravity  of  i  .029  to  i  .034,  skim-milk  above 
1.034,  and  watered  milk  below  1.029. 

37.  Lactometer  Results  Liable  to  Error. — The  results 
obtained  by  the  lactometer  are  liable  to  error,  not  on 
account  of  any  imperfection  in  the  principle  or  instru- 
ment, but  because  of  the  complex  composition  of  milk. 
When  sugar  is  mixed  with  water,  the  richness  of  the 
solution  in  that  one  substance  can  be  as  accurately  and 
quickly  determined  by  the  hydrometer  as  by  any  other 
means.  But  when  instead  of  one  substance  there  are 
several  mixed  with  water,  and  especially  when  some  of 
these  substances  make  the  liquid  less  dense,  while  others 
make  it  more  dense,  the  liability  to  error,  in  estimating 
with  the  lactometer  the  proportion  of  any  one  of  the  sub- 
stances, becomes  very  serious.  The  fat  might  first  be  re- 
moved, which  would  result  in  raising  the  gravity  ; 
then  water  might  be  added  which  would  lower  it  to 
almost  the  specific  gravity  of  normal  milk.  Hence,  if 
the  milk  were  judged  solely  by  the  lactometer,  serious 
errors  might  sometimes  result. 

38.  Effect  of  Temperature  on  Lactometer  Reading. — 
A  difference  in  temperature  affects  the  density  of  the 
milk  solution  and  causes  a  difference  in  the  depth  to 
which  the   lactometer  sinks.     In  taking  a   lactometer 


42 


THE    CHEMISTRY   OF   DAIRYING. 


Svkkft^ 


\6frm 


reading  the  temperature  of  the  milk  should  also  be  taken 
and  the  necessary  corrections  made  accord- 
ing to  the  tables  which  usually  accompany 
the  lactometer.  In  case  there  are  notables,  ap- 
ply the  general  rule.  When  the  temperature 
is  greater  than  60°  F.  (not  exceeding  15°) 
add  0.1  for  each  lactometer  degree  greater 
than  60°,  as  specific  gravity  1.032  at  70°; 
70 — 60=10;  10X0.1=  I  to  be  added  to  32 
makes  the  specific  gravity  1.033  at  60°  F. 
When  the  temperature  is  less  than  60°  subtract 
this  factor  from  the  reading.  All  the  read- 
ings are  recorded  for  the  temperature  of  60° 
F.    [See  appendix  for  table.] 

The    lactometer   in   most    general    use   is 
known  as  Quevenne's  lactometer.     There  are 
other  forms,    one  known  as  the  New  York 
State  Board  of  Health  lactometer,  which  has 
a  scale  divided  into  1 10  parts,  100  being  for  nor- 
mal milk.    In  purchasing  a  lactometer,  always 
get  one  that  has  a  thermometer  attached,  as 
they  are  the  most  reliable  ones.    A  lactometer 
reading  by  itself  is  not  as  valuable  as  when 
taken  in  connection  with  the  Babcock  test. 
39.  Combined  Uses  of  Lactometer  and  Babcock  Test. 
— When  used  jointly,  the  quality  of  the  milk  can  be 
safely  judged.     The  following  general  rules  will  aid  in 
judging  milk  : 

A  low  fat,  2.50  per  cent.,  and  a  high  specific  gravity,  1.035,  in- 
dicates skimming  or  fats  removed. 


SOLIDS   IN    MILK. 


43 


A  low  fat,  3.00  per  cent.,  and  a  low  specific  gravity,  1.027,  indi. 
cates  watered  milk. 

A  low  fat,  2.50  per  cent.,  and  a  normal  gravity,  1.029,  indicates 
skimmed  and  watered. 

Fat,  4.00  per  cent.,  and  a  normal  gravity,  1.032,  indicates  nor- 
mal milk. 

Fat,  4.50  per  cent.,  and  a  normal  gravity,  1.029,  indicates  nor- 
mal milk. 

40.  Solids  in  Milk.— In  order  to  obtain  a  fair  idea  of 
the  solids  in  milk,  multiply  the  per  cent,  of  fat  obtained 


VJhole 

=3:^-= 

■^fM 

Milk 

■^f^ 

/0»9 

&^ 

h 

:^=rL 

g^ 

/.034 

^M 

^^m 

Skim  Milk 
3p.Gr.  I.  os^- 
ft  higher 


Milk 
<5pGr  leaa 
ihan  Normal 

I0Z9 


m 

wn 

ffl 

m 

Fig-  13. 


Fig.  14. 


Fig.  15. 


in  the  test  by   1.2.     Divide  the  gravity  number  by  4. 
To  the  sum  of  the  two  results  add  0.14. 

Example.— A  milk  tests  four  per  cent,  fat,  and  has  a  specific 
gravity  of  1.032.  Hence  the  gravity  number  is  32.  4  X  1.2  =4.8. 
32  -r-  8  =4.  4.8+8+  0.14  =  12.94  per  cent,  solids.  This  milk  con- 
tains approximately  12.94  per  cent,  solids. 

This  is  Hehner  and  Richmond's  formula.  This 
formula  has  been  found  by  comparison  with  chemical 
analysis  to  be  one  of  the  most  accurate  simple  formulas 
in  use. 

Babcock's  formula  for  determining  the  total  solids, 


44  THK    CHEMISTRY   OF   DAIRYING. 

and  the  solids  not  fat,  is  accurate  and  useful.     The  for- 
mula is  as  follows  : 

Solids  not  fat  =  ^  "*"  ^'^-^ 

Total  solids  =^  '^J-^ 
3-0 
Z,  =  readingof  Quevenne's  lactometer  at  60°  F.,andy=per 
cent,  of  fat. 


REFERENCES  TO  CHAPTER  V. 

1.  The  Lactometer — Its  Reliability  and  Usefulness.  Munsell : 
American  Chemical  Journal,  1888. 

2.  The  Relation  between  the  Specific  Gravity,  Fat  and  Solids 
not  Fat  in  Milk.     Richmond  :  Analyst,  17,  No.  197. 

3.  Richmond  and  Hehner's  Formula  for  Calculating  the  Solids 
of  Milk.     Analyst,  13,  No.  142. 

4.  A  Simplification  of  Richmond's  New  Formula.  Analyst, 
20,  1895. 

5.  Directions  for  Use  of  the  Babcock  Milk  Test  and  Lactom- 
eter.    Babcock  :  Wisconsin  Experiment  Station,  Bulletin  No.  36. 

6.  The  Use  of  a  Formula  for  Calculating  the  Per  Cent,  of  Total 
Solids  in  Milk.  Babcock :  Wisconsin  Experiment  Station. 
Annual  Report,  1894. 

7.  Detection  of  Adulterations  in  Milk.  Wisconsin  Experiment 
Station.     Bulletin,  No.  36. 

8.  Lactometry.     Wiley  :  Agricultural  Analysis,  3. 

9.  Fleischmann's  Formula  for  Calculating  the  Solids  or  Fat  in 
Milk.     Journal  fiir  Landwirtschaft,  Band  33. 

10.  Hehner  and  Richmond's  Formula.  Minnesota  Experi- 
ment Station,  Bulletin  No.  19. 

11.  The  Use  of  the  Lactometer  and  Milk  Test  in  Determining 
the  Character  of  Milk.  Minnesota  Experiment  Station,  Bulle- 
tin No.  19. 

12.  Fleischmann  and  Morgan's  Formula  for  Calculating  the 
Solids  of  Milk.     Milch  Zeitung,  141  No.  6. 


REFERENCES  TO  CHAPTER  V.  45 

13.  Table  for  Corrections  of  the  Temperature  in  Lactometry. 
(Centigrade  scale.)  Konig  :  Untersuchungen  in  landwirt- 
schaftlich  und  gewerblich  Wichtiger  Stoffe. 

14.  A  Simple  Formula  for  Calculating  the  Solids  not  Fat.  Bab- 
cock:  Wisconsin  Experiment  Station,  Bulletin  No.  34. 

15.  The  Adulteration  of  Milk.  Blyth  :  Foods;  Composition  and 
Analysis. 

16.  Comparison  of  Results  by  the  Use  of  the  Formulas  of  Heh- 
ner  and  Richmond,  Fleischmann,  and  Babcock,  with  the  Gravi- 
metric Method.  Report  of  the  Kighteenth  Annual  Convention 
of  the  Association  of  Official  Agricultural  Chemists,  1894. 

17.  Effect  Upon  the  Specific  Gravity  of  Milk  by  Allowing  the 
Milk  to  Stand  After  Milking.  Richmond:  Report  of  Eighteenth 
Annual  Convention  of  Association  of  Official  Agricultural  Chem- 
ists, 1894. 

18.  Lactodensimeter.  Quevenne-Miiller  :  Grandeau,  Analyse 
des  Materies  Agricoles. 

19.  The  Adulteration  of  Milk  :  Various  articles  in  the  current 
numbers  of  the  Analyst. 

20.  Legal  Cases  Relating  to  the  Adulteration  of  Milk.  Various 
and  numerous  articles  in  the  current  numbers  of  the  Milch 
Zeitung. 


CHAPTER  VI. 
Chemistry  of  Butter-Making. 

41.  Composition  of  Cream. — Cream  is  quite  variable 
in  composition.  It  ranges  in  fat  content  from  ten  to 
sixty  per  cent.  Cream  is  known  as  thick  or  thin  accord- 
ing to  the  amount  of  fat  which  it  contains.  Average 
cream  contains  from  twenty  to  twenty-five  per  cent,  fat, 
and  has  about  the  following  composition  : 

Average  Anai^ysis  of  Twenty-Five  Sampi.es. 

Per  cent. 

Water 66.41 

Solids 33.59 

Fat 25.72 

Casein  and  albumin 3.70 

Milk  sugar 3.54 

Ash 0.63 

As  a  rule  about  eighty  to  ninety  per  cent,  of  the  solid 
matter  of  cream  is  fat.  Cream  contains  casein,  albu- 
min, ash,  and  milk  sugar,  the  same  as  milk,  but  in 
smaller  proportions. 

One  hundred  pounds  of  milk  will  produce  from  fifteen 
to  twenty  pounds  of  cream,  depending  upon  the  way  in 
which  the  cream  is  obtained  and  upon  the  composition 
of  the  milk  used. 

42.  Testing  Cream. — In  testing  cream,  special  bottles 
with  a  bulb  in  the  stem  to  accommodate  the  extra  fat, 
as  showm  in  the  figure,  can  be  used  in  the  same  way  as 


LOSS   OF   FAT   IN   BUTTER-MAKING, 


47 


© 


S 


ordinary  test-bottles.  The  cream  test-bottles  are  in 
every  way  capable  of  taking  the  place  of  the 
' '  oil-test ' '  and  will  be  found  to  give  more  re- 
liable results.  In  testing  cream  the  utmost 
care  should  be  used  to  obtain  a  fair  sample. 
Rinse  the  pipette  with'a  little  warm  water  so 
as  to  get  all  of  the  cream.  The  cream  can  be 
measured  into  the  test-bottles  by  the  cream 
gatherers,  while  the  cream  is  still  sweet.  It 
is  alvery  difficult  matter  to  sample  old  and 
lumpy  cream.  The  test-bottles  for  cream  can 
be  obtained  from  the  supply  houses  which 
deal  in  chemicals  and  glassware. 

The  cream  should  contain  at  least  ninety- 
seven  per  cent,  of  the  total  fat  in  the  milk. 
When  the  cream,  obtained  by  the  separator  Fig.  16. 
contains  less  than  ninety-five  per  cent,  of  the  total  fat 
there  is  too  great  a  loss  of  butter-fat.  Separator  cream 
differs  in  no  essential  way  from  the  cream  obtained  by 
the  gravity  process. 

43.  Loss  of  Fat  in  Butter=Making. — In  butter-making 
the  loss  of  the  butter-fat  is  one  of  the  most  important 
matters  to  consider.  The  greatest  loss  of  butter-fat  oc- 
curs in  the  skim-milk.  There  is  a  total  loss  of  four  or 
five  times  more  fat  in  the  skim-milk  than  in  the  butter- 
milk. Hence  the  necessity  for  the  best  methods  of 
creaming  and  the  observance  of  the  requisite  conditions 
for  obtaining  the  cream. 

The  three  methods  by  which  the  cream  is  usually  ob- 
tained are  :  shallow  setting,  cold  deep  setting,  and  the 


48  THE    CHEMISTRY   OF    DAIRYING. 

separator.  When  the  milk  is  set  in  shallow  pans  and 
the  cream  is  removed  by  hand  skimming,  there  may  be  a 
loss  of  fat  in  the  skim-milk,  amounting  to  from  one-half  to 
three-quarters  of  a  pound  of  fat  for  every  hundred  pounds 
of  milk  used.  This  loss  depends  upon  a  number  of  con- 
ditions, such  as  the  length  of  time  the  cow  has  been  in 
milk,  the  season  of  the  year,  and  the  temperature  of  the 
room  where  the  pans  are  set.  It  is  possible  to  do  good 
creaming  work  with  shallow  setting,  as  in  pans,  but 
ordinarily  the  necessary  conditions  for  successful  cream- 
ing by  this  method  are  not  observed.  For  thorough 
creaming,  a  low  temperature  is  very  essential.  The  loss 
by  shallow  setting  may  amount  to  one-fifth  or  more  of 
the  total  fat  of  the  milk,  or  eighty  per  cent,  and  less  of 
the  fat  being  recovered  in  the  cream. 

In  case  the  milk  is  set  in  deep  pails  which  are  im- 
mersed in  water  at  40°  to  44°  F.,  the  loss  can  be  reduced 
to  about  two-tenths  of  a  pound  of  fat  for  every  hundred 
pounds  of  the  milk  used.  The  skim-milk  will  then 
show  from  two-tenths  to  four  tenths  per  cent,  of  fat.  A 
loss  of  0.25  per  cent,  of  fat  in  the  skim-milk  is  equiva- 
lent to  a  loss  of  five  to  seven  per  cent,  and  more  of  the 
total  fat,  depending  upon  the  richness  of  the  whole  milk 
in  fat. 

By  means  of  the  separator  the  loss  of  fat  may  be  re- 
duced to  one  and  one-half  or  two  per  cent,  of  the  total 
fat. 

Inasmuch  as  the  creaming  of  milk  by  the  cold  deep 
setting  process  is  inexpensive  and  within  the  reach  of 
every   one,  it  might  be  well  to  briefly  state  the  main 


LOSS   OF   FAT   IN   BUTTKR-MAKING. 


49 


points  of  the  process.  When  the  milk  is  set  in  pails, 
twenty  inches  deep  and  eight  inches  or  so  in  width,  and 
the  pails  are  placed  in  a  trough  or  tank  of  ice  water, 
creaming  begins  immediately.  The  milk  first  becomes 
poorer  in  fat  at  the  bottom  of  the  can,  where  the  tem- 
perature is  first  lowered  to  the  greatest  extent.  Within 
fifteen  minutes  after  the  milk  is  set,  the  temperature  of 
the  milk  in  the  bottom  section  of  the  ca'n  will  drop  to  40° 
and  will  contain  less  fat,  the  fat  having  passed  into  the 
upper  layers.  The  middle  section  of  milk  is  next 
effected,  and  during  the  entire  time  of  creaming  it  has 
an  intermediate  temperature  and  fat  content. 

The  creaming  action  goes  on  very  rapidly  for  the  first 


VJafer^- 


Milk 


Milk 


Fig.  17. 

six  hours  when  the  temperature  of  the  water  is  kept 
down.  If  the  temperature  of  the  tank  water  is  not  suffi- 
ciently low,  below  44°,  the  creaming  action  is  much 
slower  and  the  milk  finally  becomes  "clogged,"  and 
there  is  a  heavy  loss  of  fat  in  the  skim-milk. 

The  temperature  of  the  water  at  the  time  the  milk  is 
set  is  of  far  more  importance  than  the  temperature  of  the 
milk.     A  difference  of  10°  in  the  temperature  of  the  milk 


50  THE   CHEMISTRY   OF    DAIRYING. 

when  it  is  set  does  not  appreciabl}'  effect  the  thorough- 
ness of  the  creaming,  while  a  difference  of  5°  in  the  tank 
water  seriously  affects  the  creaming.  When  a  cow  is 
fresh  in  milk  and  the  temperature  of  the  tank  water 
is  kept  down  to  44°  or  lower,  the  skimming  can 
safely  be  done  in  twelve  hours,  provided  the  pails  are 
needed  for  the  next  milking,  otherwise  twenty-four 
hours  should  be  allowed  for  the  creaming.  A  slight 
gain  can  be  obtained  from  a  prolonged  setting,  but  in  no 
case  will  this  equal  the  loss  sustained  for  the  want  of  a 
low  temperature  at  the  beginning  A  prolonged  setting 
can  not  make  up  for  the  want  of  a  low  temperature  at 
the  time  of  setting. 

For  the  purpose  of  comparison,  figures  are  given, 
showing  the  rate  of  creaming  of  two  milks,  one  under 
good  and  the  other  under  poor  conditions  : 

Good  Poor 

conditions,  conditions. 

Tank  water  40°  Tank  water  60° 

Per  cent.  Per  cent. 

Fat  in  milk 5.00  4,45 

Top  below  4  inches  30  minutes 4.60  4.40 

Middle                           "         "         4.45  4.40 

Bottom                          "         "        3,40  4.40 

Top                              I  hour  4.00  4.30 

Middle                              "       3.85  4.30 

Bottom                             "       1,30  2.92 

Top                              2  hours 3.30  3.90 

Middle                               "       2.10  3.90 

Bottom                             "       0.75  2.40 

Top                              5I  hours 1.40  3.00 

Middle                             "       i  .00  2 .90 

Bottom                             '*       0.35  2.18 

Top                              10  hours 0.40  2.52 

Middle                             "       0.30  2.40 

Bottom                             "       0.15  1.40 

Average  fat  in  skim-milk 0.25  i  .40 


LOSSES   OF    MILK   FATS   IN   BUTTKR-MAKING.         5 1 

Observe  how  much  more  slowly  and  incompletely  the 
cream  rises  in  the  can  set  at  60°.  Notice  also  the 
greater  loss  of  fat  in  the  skim-milk. 

44.  Losses  of  flilk  Fats  in  Butter-flaking. — When 
100  pounds  of  milk  are  creamed,  about  eighty  pounds 
of  skim-milk  and  twenty  pounds  of  cream  are  obtained. 
If  the  milk  tests  about  fourper  cent,  fat,  and  the  cream  is 
carefully  churned,  it  will  make  about  4.60  pounds  of 
butter.  The  following  table  shows  how  the  various 
constituents  of  100  pounds  of  milk  are  distributed  when 
the  milk  is  made  into  butter.  With  poor  work,  of 
course,  a  much  smaller  amount  of  fat  is  recovered  in  the 
butter,  and  more  is  lost  in  the  skim-milk  and  buttermilk. 

Distribution  OF  M11.K  Sowds  in  Butter- Making. 

Products  from  100  pounds  of  milk. 
100  pounds  Cream     Skim-  Butter- 

of  milk.  20.         milk.      Butter,     milk. 

Total  solids 13.00  5.18  7,82  4.00  1.18 

Fat 4.00  3.88  0.12  3.83  0.05 

Casein,  albumin  ..     3.50  0.50  3.00  o.io  0.40 

Sugar  and  acid 4.75  0.75  4.00  0.05  0.70 

Ash 0.75  0.05  0.70  ...  0.03 

The  four  pounds  of  solid  matter  recovered  in  the  but- 
ter, which  contains  3.83  pounds  of  fat,  together  with  the 
salt  and  water  which  the  butter  contains,  will  make  about 
4.6  pounds  of  marketable  product. 

About  ninety-six  per  cent,  of  the  total  fat  of  the  milk 
is  recovered  in  the  butter.  About  three  times  more 
fat  is  lost  in  the  skim-milk  than  in  the  buttermilk.  Nearly 
ninety  per  cent,  of  the  casein  and  albumin,  and  eighty- 
five  per  cent,  of  the  milk  sugar  find  their  way  into  the 


52  THE    CHEMISTRY   OF    DAIRYING. 

skim-milk.  The  buttermilk  is  composed  of  constituents 
present  in  the  cream,  minus  what  has  been  removed  in 
the  butter.  About  seven  per  cent,  of  the  ash  of  the  milk 
goes  into  the  cream.  The  buttermilk  contains  about  ten 
per  cent,  of  the  original  casein  and  albumin  and  about 
fifteen  per  cent,  of  the  milk  sugar.  The  composition 
and  comparative  food  value  of  skim-milk  and  butter- 
milk will  be  considered  in  another  part  of  this  work. 

With  poor  butter-making  the  amount  of  casein  and 
foreign  matter  left  in  the  butter  is  increased.  A  large 
amount  of  water  and  foreign  matter  left  in  the  butter 
greatly  decreases  its  keeping  qualities,  because  fermen- 
tation can  then  proceed  more  rapidly  than  when  these 
substances  are  not  present.  Pure  fat  ferments  very 
slowly  ;  with  water  and  casein  present,  the  fermentation 
is  more  rapid. 

45.  Churning. — In  churning,  the  massing  together  of 
the  fat  is  supposed  to  be  due  to  the  hardening  of  the  fat 
globules  ;  the  globules  lose  their  spherical  form  and  ap- 
pear as  masses  which  are  irregular  in  shape  and  have 
sharp  angles.  Ordinarily  the  fat  globules  are  spherical, 
and  the  surface  tension  prevents  their  massing.  When 
of  angular  form,  the  fat  particles  are  more  easily  united. 
The  large  globules  unite  first  into  larger  masses.  The 
smaller  globules  are  the  last  to  assume  irregular  forms 
and  to  mass  together.  The  agitation  of  churning  aids 
the  combination  of  the  irregular  masses.  The  agitation 
causes  a  change  of  the  fat  globules  from  a  liquid  to  a 
solid  condition.  This  is  entirely  a  physical  change  and 
will  take  place  only  at  the  right  temperature.     Frozen 


THE   COMPOSITION   OF   BUTTER.  53 

milk  or  cream  churns  very  easily  because  then  the  glob- 
ules are  irregular  in  form  and  are  in  a  solid  condition, 
but  the  churning  is  not  so  complete  as  at  a  higher  tem- 
perature. 

The  ripening  of  the  cream  is  supposed  to  aid  in  ren- 
dering less  resistance  to  the  massing  of  the  fat  globules. 
When  the  cream  is  well  ripened,  the  serum  is  reduced  in 
specific  gravity,  because  the  casein  is  coagulated  by  the 
acid  formed  in  ripening  and  the  surface  tension  is  there- 
by decreased. 

The  temperature  of  churning  depends  upon  ( i )  the 
ripeness  of  the  cream,  and  (2)  size  and  character  of  the 
fat  globules.  Sweet  cream  churns  between  50°  and  55^  ; 
sour  cream  from  58°  to  68°.  Mixing  sweet  and  sour 
cream  is  not  a  good  practice,  it  being  preferable  to  have 
the  cream  all  of  the  same  degree  of  ripeness,  for  then 
the  butter  comes  more  evenly  and  there  is  no  overchurn- 
ing  of  a  part  of  the  butter.  The  more  advanced  the 
period  of  lactation  the  smaller  the  globules  and  the 
higher  the  temperature  necessary  for  churning. 

46.  The  Composition  of  Butter.— The  composition  of 
twenty  samples  of  butter  analyzed  at  the  Minnesota  Ex- 
periment Station,  is  given  in  the  following  table  : 

Average.  Highest.  Lowest. 

Percent.  Percent.         Percent. 

Water 12. (xd  16.20  8.21 

Fat 85.00  90.20  79.42 

Ash  and  salt 2.25  3.09  0.44 

Casein  and  milk  sugar. .     0.75  2.09  0.21 

Butter  should  contain  not  more  than  fifteen  per  cent. 


54  THE    CHEMISTRY   OF   DAIRYING. 

water,  nor  less  than  eighty-three  per  cent.  fat.  The 
amount  of  water  that  can  be  retained  in  butter  depends 
upon  the  ripeness  of  the  cream,  temperature  of  churn- 
ing, washing  and  working  of  the  butter.  Sweet 
cream  butter  will  usually  retain  more  casein  and  water 
than  butter  made  from  sour  cream.  The  effects  of  dif- 
ferent temperatures  of  churning,  working  and  washing 
upon  the  amount  of  water  left  in  the  butter  is  illustrated 
in  the  following  table  : 

Per  cent,  water  Temperature  of 

Name  of  cow.  in  butter.      Churning.   Washing.    Working. 

Beckley 8.95  66  59  59 

Bess 9-75  64  54  56 

Bess 8.52  62  59  59 

Houston 10.22  64  55  59 

Houston 10.44  63  53  59 

Maria 9.75  64  55  58 

Olive 9.25  62  56  58 

Olive 8.71  62  56  60 

Sully 8.22  62  60  62 

Sweet  Briar 10.42  64  55  58 

Sweet  Briar 8.80  •  •  62  63 

Topsy 9.06  62  59  63 

Topsy 8.00  64  58  62 

It  appears  that  the  higher  the  temperatures  reached 
in  either  churning,  w^ashing  or  working,  the  less  the 
amount  of  water  retained  in  the  butter.  The  warmer 
the  butter,  the  more  easily  it  parts  with  its  water,  and 
the  more  thoroughly  is  the  water  worked  out. 


REFERENCES  TO  CHAPTER  VI. 
I.  The   Composition    of    Cream.     Massachusetts  Experiment 
Station  Reports,  1889,  1890,  1892,  1893. 


REFERENCES  Ta  CHAPTER   VI.  55 

2.  Testing  Cream  and  Milk.  Maine  Experiment  Station, 
Bulletin  No.  4. 

3.  Testing  Cream  by  the  Babcock  Test.  Connecticut  Experi- 
ment Station  (New  Haven)  Eighteenth  Annual  Report. 

4.  The  Babcock  Test  as  a  Basis  for  Payment  in  Cream-Gather- 
ing Creameries.  Connecticut  Experiment  Station  (New  Haven), 
Bulletin  No.  119. 

5.  The  Composition  of  Cream.  Konig  :  Chemie  der  Mensch- 
lichen  und  Genussmittel,  Band  11. 

6.  Testing  Milk  at  Creameries.  Vermont  Experiment  Station, 
Bulletin  No.  16. 

7.  Purchasing  Milk  by  Test.  Delaware  Experiment  Station, 
Seventh  Annual  Report. 

8.  Test  of  Cream  Separators.  Cornell  University  Experiment 
Station,  Bulletins  Nos.  66  and  105. 

9.  Tests  of  Dairy  Apparatus.  Vermont  Experiment  Station, 
Bulletin  No.  27  and  Sixth,  Seventh  and  Eighth  Annual  Reports. 

10.  Test  of  Cream  Separators.  Pennsylvania  Experiment  Sta- 
tion, Bulletins  Nos.  20  and  21,  Annual  Report,  1895. 

11.  Report  on  Separators,  Gravity,  Creaming,  etc.  Iowa  Ex- 
periment Station,  Bulletin  No.  25. 

12.  Tests  of  Dairy  Implements.  North  Carolina  Experiment 
Station,  Bulletin  No.  114. 

13.  Hand  Power  Cream  Separators.  Delaware  Experiment 
Station,  Bulletin  No.  27,  Fifth  Annual  Report. 

14.  Cream  Raising  by  the  Cold  Deep  Setting  Process.  Min- 
nesota Experiment  Station,  Bulletin  No.  19. 

15.  Creaming  of  Milk.  Article  in  Handbook  of  Experiment 
Station  Work. 

16.  Creaming  Experiments.  Babcock:  Wisconsin  Experiment 
Station,  Bulletin  No.  29. 

17.  Loss  of  Fat  in  Butter-making.  Iowa  Experiment  Station, 
Bulletin  No.  11. 

18.  Loss  of  Fat  in  Butter-making,  with  Increase  in  Lactation 
Period.     New  York  State  Experiment  Station  Report,  1891. 


56  THE    CHEMISTRY    OF    DAIRYING. 

19.  Butter  Production  from  Milk  at  Different  Periods  of  Lac- 
tation.    Maine  Experiment  Station  Report,  1889. 

20.  Loss  of  Fat  in  Butter-making.     Article  on  Butter-making 
in  Handbook  of  Experiment  Station  Work. 

21.  Composition  of  the   Slime   from    the    Centrifugal  Bowl. 
Fleischmann. 

22.  Butter-making.     Fleischmann :  Lehrbuch   der  Milchwirt- 
schaft. 

23.  Churning  and  Butter-making.     Gurler  :  American  Dairy- 
ing. 

24.  Churning.     Article  in  Handbook  of  Experiment  Station 
Work. 

25.  Churning  Experiments.     Iowa  Experiment  Station,  Bul- 
letin No.  22. 

26.  On  the  Churning  Process  and  the  Formation  of  Butter. 
A.  Jscher  Kasserd  :  Milch  Zeitung,  No.  23,  1894. 

27.  The  Temperature  of  Churning  Sweet  and   Sour  Cream. 
New  York  State  Experiment  Station  Report,  1889. 

28.  Tests  of  Box  and  Barrel  Churns.     Vermont  Experiment 
Station,  Bulletin  No.  27. 

29.  The  Acidity  of  the  Cream  and  the  Yield  of  Butter.  Illinois 
Experiment  Station,  Bulletin  No,  9. 

30.  Churning  the  Cream  from  Cows  at  Different  Periods  in  Lac- 
tation.    Haecker  :  Houd's  Dairyman,  1894. 

31.  Butter-making.      Powrian  :    La  lartiere  :    Art  de  traiter  le 
lait,  de  fabrique  le  beurre  et  les  princepaux  fromages. 

32.  The  Composition  of  Butter.     Minnesota  Experiment  Sta- 
tion, Bulletin  No.  19. 

33.  Composition  of  Butter.      Wisconsin  Experiment  Station, 
Annual  Report,  1889. 

34.  Composition  of  Butter.     Massachusetts  State  Station,  An- 
nual Report,  1889. 

35.  Composition  of  Butter.    Pennsylvania  Experiment  Station, 
Annual  Report,  1893. 

36.  The  Composition  of  Butter.     Connecticut  State  Station, 
Annual  Report,  1892. 


RKFERKNCES   TO   CHAPTER   VI.  57 

37.  Composition  of  Sweet  Cream  Butter.     West  Virginia  Ex- 
periment Station,  Annual  Report,  1890. 

38.  Composition  of  Sweet  and  Sour  Cream  Butter.     Iowa  Ex- 
periment Station,  Bulletin  No.  18. 

39.  The    Composition   of   Butter    from    Different    Countries. 
Konig  :  See  reference  No.  6. 

40.  Abnormal  Amounts  of  Water  in  Butter— IvCgal  Cases.  Cur- 
rent numbers  of  the  Analyst. 


CHAPTER  VII. 
The  Chemistry  of  Cheese-Making. 

47.  The    Nitrogenous   Compounds    of    Milk.  —  The 

casein  and  albumin  in  milk  are  nitrogenous  compounds 
and  are  sometimes  spoken  of  as  the  proteids  of  milk. 

The  compounds  previously  considered  as  sugar  and  fat, 
contained  only  carbon,  hj^drogen  and  oxygen,  and  they 
are  sometimes  called  the  non-nitrogenous  compounds  of 
milk,  because  the}^  contain  no  nitrogen.  The  nitroge- 
nous compounds  are  those  that  contain  the  element 
nitrogen,  and  in  some  cases  other  elements  together 
with  carbon,  hydrogen  and  ox3^gen.  Casein  and  albu- 
min are  the  two  most  important  nitrogenous  compounds 
in  milk.  These  proteids,  as  they  are  sometimes  called, 
are  alike  in  their  general  composition,  but  differ  in  the 
number  of  their  building  materials  or  elements,  and  the 
way  in  which  they  are  combined.  The  proteids  or  pro- 
tein compounds  are  the  general  class,  while  the  casein 
and  albumin  are  each  distinct  representatives  of  a  sepa- 
rate sub-class.  In  addition  to  casein  and  albumin  there 
are  smaller  amounts  of  other  milk  proteids  present,  as 
well  as  smaller  amounts  of  other  nitrogenous  compounds 
which  are  not  proteids.  For  dair^-  purposes  it  is  neces- 
sary to  consider  the  main  chemical  and  physical  prop- 
erties of  each  group,  because  they  illustrate,  to  a  great 
extent,  the  underlying  principles  of  cheese-making. 

48.  Casein. — When  milk  is  fresh,   the  casein  is  in  a 


AI.BUMIN.  59 

semi-soluble  form,  but  as  soon  as  a  sufficient  amount  of 
lactic  acid  is  formed  by  the  fermentation  of  the  milk 
sugar,  curdling  results,  or  more  correctly  speaking,  the 
lactic  acid  precipitates  the  casein. 

Many  other  acids  like  acetic  acid  (the  acid  in  vinegar) 
hj^drochloric  acid  and  sulphuric  acid,  will  produce  the 
same  result ;  that  is,  precipitate  or  throw  down  the 
casein. 

The  point  to  be  noted  is  :  Dilute  acids  added  to  milk 
in  small  amounts,  precipitate  the  casein,  but  they  do  not 
precipitate  the  albumin.  In  precipitating  the  casein  a 
part  of  the  acid  unites  with  the  casein.  Some  of  the  ash 
of  the  milk  is  also  combined  and  precipitated  with  the 
casein. 

49.  Albumin.— After  milk  has  fully  soured  it  will 
separate  into  a  watery  portion,  whey,  which  contains  the 
albumin  and  milk  sugar,  and  a  coagulated  portion  that 
includes  the  casein  and  fat.  When  this  liquid  or 
whey  is  poured  off  or  filtered,  and  the  clear  solution 
boiled,  a  flake-like,  yellowish- white  substance  will  be  ob- 
served, which  is  the  albumin.  The  albumin  may  also 
be  obtained  by  taking  a  sample  of  milk,  adding  a  few 
drops  of  acetic  acid,  or  strong  vinegar,  to  the  milk,  so 
as  to  coagulate  the  casein,  and  then,  after  thorough 
mixing,  filtering.  The  clear  filtrate  (filtered  liquid)  is 
heated  to  157°  F.,  when  the  solution  turns  white,  due  to 
the  coagulating  of  the  albumin.  The  acid  that  forms 
when  the  milk  sours  does  not  separate  the  albumin, 
but  it  does  separate  the  casein.  The  albumin  in  milk  is 
coagulated  at  157°  to  161°  F. 


6o  THE    CHEMISTRY   OF    DAIRYING. 

The  leathery,  skin-like  mass,  that  forms  on  milk  when 
it  is  boiled,  is  albumin. 

According  to  Bl3'th,  there  is  a  constant  ratio  between 
the  albumin  and  casein  in  normal  milk.  In  cheese- 
making,  by  the  ordinary  process,  the  albumin  is  not 
recovered.  Albumin  is  coagulated  by  a  number  of 
chemicals,  as  mercuric  chloride  and  lead  acetate,  both 
of  which  are  poisons. 

50.  Rennet. — In  cheese-making,  the  casein  is  coagu- 
lated by  rennet.  Rennet  is  prepared  from  the  mem- 
brane or  lining  of  the  fourth  stomach  of  the  calf.  Rennet 
contains  various  digestive  fluids  and  organisms,  chief 
among  them  being  the  peptic  and  lactic  ferments  from 
the  gastric  juice.  Rennet  imparts  to  the  milk  (i)  lac- 
tic, peptic  and  other  ferments,  (2)  acids  produced  by  the 
ferments.  In  cheese-making  it  would  not  be  practicable 
to  allow  the  milk  to  become  sour  and  curdle  from  pro- 
longed fermentation,  because  objectionable  ferments 
would  then  form  in  the  milk,  along  w^ith  the  desirable 
ones.  The  action  of  rennet  on  milk  is  similar  to  the  ac- 
tion of  weak  or  dilute  acids  which  coagulate  the  casein 
combined  w4th  the  power  possessed  by  the  digestive  fer- 
ments that  are  found  in  the  rennet  and  which  serve  to 
ripen  the  cheese. 

The  temperature  at  which  the  rennet  is  added,  86°  to 
90°  F.,  is  very  favorable  for  the  full  development  and 
digestive  action  of  the  various  ferments,  introduced  along 
with  the  rennet. 

51.  Rennet  Test. — In  cheese-making  the  rennet  test  is 
employed  to  determine  when  the  milk  is  in  the  proper 


THE   HOT   IRON   TEST.  6 1 

condition  for  adding  the  rennet.  The  test  is  made  in 
the  following  way  :  Five  cc.  of  rennet  extract  is  put  into 
a  flask  and  water  added  until  the  solution  measures  fifty 
cc.  ;  it  is  then  thoroughly  mixed.  A  small  cup  wnth  a 
mark  on  the  side,  140  cc,  is  floated  in  the  center  of  the 
milk  vat.  The  cup  is  filled  to  the  mark  with  milk  from 
the  vat.  Five  cc.  of  the  diluted  rennet  is  then  added  to 
the  milk  in  the  cup  and  thoroughly  stirred.  The  milk 
in  the  cup  is  closely  observed,  and  when  a  knife  is  drawn 
from  the  milk  and  the  proper  signs  of  coagulating  ob- 
served, the  time  required  for  curdling  is  noted.  If  the 
milk  requires  more  than  sixty  seconds  for  coagulating, 
it  is  not  ripe  enough  to  add  the  rennet.  The  milk  is 
then  allowed  to  ripen  farther  or  more  starter  is  added. 
If  milk  shows  signs  of  coagulating  in  less  than  forty-five 
seconds,  it  is  over-ripe.  The  riper  a  milk  is,  the  shorter 
the  time  required  for  the  process  of  making,  and  the  re- 
sult is  a  quick-curing  cheese. 

The  ripeness  of  the  milk,  as  shown  by  the  rennet  test, 
has  a  great  deal  to  do  with  the  ripening  of  the  cheese. 
The  ripening  of  the  curd  in  the  vat  also  influences  the 
ripening  and  keeping  qualities  of  the  cheese. 

52.  The  Hot  Iron  Test  is  employed  to  determine  the 
degree  of  ripeness  of  the  curd.  As  soon  as  the  casein  is 
precipitated,  or  as  the  factory  man  would  say,  as  soon  as 
the  curd  has  set,  the  rennet  causes  other  chemical  and 
bacteriological  changes  to  begin,  similar  to  the  first 
stages  of  the  digestion  of  the  food  in  the  stomach.  The 
curd  changes  from  a  hard  leather}^  mass  to  a  soft,  stringy 
consistency.     The  change  is  carefully  watched  by  the 


62  THE   CHEMISTRY   OF    DAIRYING. 

cheese-maker,  who  uses  for  this  purpose  the  hot  iron 
test. 

When  the  little  threads,  as  shown  by  putting  a  piece  of 
curd  against  the  hot  iron  and  then  withdrawing  it,  are 
an  eighth  of  an  inch  in  length,  the  whey  is  usually 
drawn  off,  and  the  curd  is  allowed  to  digest  still  farther 
until  the  threads  are  about  one-fourth  of  an  inch  long, 
w^hen  the  process  is  stopped  by  grinding  and  salting  the 
curd.  The  ferments  that  were  added  in  the  rennet  are 
the  agents  that  carry  on  this  work.  The  ripening  of  the 
cheese  for  market  is  simply  a  continuation  by  the  rennet 
ferments  of  this  digestive  process,  in  the  curing  room. 
Heavy  salting  checks  the  ripening  process  simply  be- 
cause the  ferments  can  not  thrive  in  a  strong  salt  solu- 
tion. The  stringing  on  the  hot  iron  is  not  due  to  the  acid 
that  is  formed,  but  is  simply  due  to  the  digestive  process 
having  reached  that  stage  where  the  hot  iron  will  show 
threads  an  eighth  to  one-fourth  of  an  inch  long. 

53.  Notes  on  the  Process  of  Cheese=naking.  —  In 
order  to  discuss  this  subject  it  will  be  necessary  to  briefly 
review  the  more  important  operations  of  cheese-making. 

The  milk  when  it  is  received  should  be  carefully 
weighed  and  a  two-ounce  sample  taken  for  testing.  The 
condition  of  the  milk  when  received  should  be  carefully 
noted,  because  a  little  foul  milk  w^hen  mixed  with  a 
large  amount  of  good  milk,  will  spoil  all  of  the  good 
milk.  The  taste  and  smell  of  the  milk  should  also  be 
noted.  Tainted  or  bad  flavored  milk  cannot  be  made 
into  a  good  cheese. 

The  milk,  after  it  is  received  and  weighed,  is  run  into 


NOTES  ON   THE   PROCESS   OF    CHEESE-MAKING.      6^ 

the  vat  and  thoroughly  mixed.  The  steam  is  turned 
on,  or  the  milk  is  otherwise  heated  in  the  vat  until  a 
temperature  of  86°  to  88°  is  reached.  The  milk  should 
be  heated  gradually  and  stirred  to  prevent  the  separa- 
tion of  the  fat  or  the  unequal  heating  of  the  milk.  When 
the  milk  reaches  the  desired  temperature,  86°  to  88°,  the 
rennet  test  is  applied.  See  Section  51.  If  the  milk  is 
found  to  be  in  the  proper  condition,  the  remainder  of  the 
rennet  is  added  at  the  rate  of  three  to  five  ounces  of  ren- 
net per  1,000  pounds  of  milk.  The  rennet  is  added  to 
a  dipper  nearly  filled  with  water  at  86°  F.  and  then  thor- 
oughly mixed  with  the  milk  in  the  vat.  When  the  milk 
is  rich  in  fat,  it  is  set  at  the  higher  temperature,  and  the 
larger  quantity  of  rennet  is  used.  The  temperature  of 
setting  and  the  quantity  of  rennet  depend  upon  the  sea- 
son of  the  year,  the  temperature  of  the  room,  conditions 
of  the  milk,  and  the  time  when  the  cheese  is  to  be  ready 
for  market.  These  are  factors  that  cannot  be  determined 
by  rules,  but  must  be  known  and  carefully  followed  by 
the  cheese-maker. 

After  the  rennet  has  been  added  and  thoroughly 
mixed,  the  milk  is  allowed  to  remain  quiet,  and  the  vat 
is  covered  until  the  curd  is  well  formed.  When  the 
index  finger  can  be  removed  from  the  curd  so  that  the 
curd  will  break  square  across  the  finger,  the  mass  is  in 
the  proper  condition  to  be  cut  with  the  cutting  knife 
into  little  cubes.  After  cutting,  the  mass  is  gently  stirred 
with  the  hands  for  about  five  minutes,  and  as  soon  as 
the  curd  is  in  the  proper  condition,  the  temperature  is 
gradually  raised  about  2°  every  five  minutes  until  the 


64  THE    CHEMISTRY   OF    DAIRYING. 

thermometer  shows  102°.  With  different  kinds  of  milk 
different  temperatures  will  be  required.  The  stirring  is 
to  be  continued  at  intervals  until  the  particles  will  no 
longer  mass  and  pack. 

As  soon  as  the  curd  shows  the  proper  signs  of  ripen- 
ing, with  the  hot  iron  test,  the  whej^  is  drawn  off.  The 
curd  packs  into  large  masses,  which  are  cut  into  blocks 
and  are  occasionally  turned  so  that  an  even  temperature 
will  be  maintained.  When  the  threads  on  the  hot  iron 
are  of  the  desired  length,  the  curd  is  ground  and  salted 
and  returned  to  the  vat,  and  after  another  short  stage  of 
digestion  it  is  put  into  molds  and  pressed.  After 
pressing  it  is  weighed,  branded  and  taken  to  the  curing 
room. 

Two  types  of  milk  should  be  followed  through  the  pro- 
cess. The  following  blank  is  used  in  making  the 
entries  required  : 

Cheese  Report. 

Size  of  vat. 

Condition  of  fat. 

Pounds  of  milk  in  vat. 

Per  cent,  of  fat  in  milk. 

Rennet  test  for  ripeness. 

Temperature  of  milk  when  set. 

Amount  of  rennet  used. 

Rate  of  rennet  per  1,000  pounds  of  milk. 

Time  cut. 

Minutes  in  curdling. 

Time  heat  is  applied. 

Time  required  to  raise  to  102*^. 

Hot  iron  test  when  dipped. 

Time  dipped. 

Time  from  cutting  to  dipping. 


MII^K   SOLIDS   IN    CHEKSK-MAKING.  65 

Pounds  of  whey. 

Per  cent,  of  fat  in  whey. 

Time  ground. 

Hot  iron  test  when  ground. 

Time  salted. 

Amount  of  salt  in  curd. 

Rate  of  salt  per  1,000  pounds  of  milk. 

Time  put  to  press. 

Time  dressed. 

Time  pressed. 

Weight  of  green  cheese. 

Weight  of  milk  per  pound  of  cheese. 

Weight  of  milk  per  pound  of  cured  cheese. 

Remarks. 

54.  Where  the  flilk  Solids  Go  in  Cheese=naking. — 

As  previously  stated,  a  hundred  pounds  of  milk  ordi- 
narily contain  from  12.5  to  13  pounds  of  dry  solid 
matter.  This  solid  matter  is  composed  of  three  and  one- 
half  to  four  pounds  of  fat,  3.25  to  3.75  pounds  of  casein 
and  albumin,  4.75  pounds  of  milk  sugar,  0.75  pound  of 
ash,  and  at  the  time  the  rennet  is  added  there  is  about 
0.16  of  a  pound  of  lactic  acid. 

When  the  whey  and  drippings  at  the  cheese  press  are 
analyzed,  it  will  be  found  that  nearly  half  of  the  solid 
matter  of  the  milk  is  recovered  in  the  dry  matter  of  the 
cheese.  Of  the  three  to  four  pounds  of  fat  in  the  milk, 
from  one-quarter  to  one-third  of  a  pound  is  lost  in  the 
whey,  which  amounts  to  from  five  to  ten  per  cent,  of  the 
total  fat.  In  good  cheese-making  there  is  about  the 
same  loss  of  butter-fats  as  in  ordinary  butter-making, 
but  a  greater  loss  than  with  good  butter-making.  The 
casein  and  albumin  are  not  so  economically  recovered  as 


66  THE   CHEMISTRY   OF   DAIRYING. 

the  milk  fats.  The  whey  shows  a  loss  of  0.75  to  0.90  of 
a  pound  milk  proteids  for  every  100  pounds  of  milk  used. 
This  loss  is  mainly  albumin,  which  is  not  coagulated  bj^ 
the  rennet.  But  little  of  the  milk  sugar  is  retained  in 
the  cheese  ;  out  of  the  4.75  pounds  of  milk  sugar  in  the 
100  pounds  of  milk  used,  from  four  and  three-tenths  to 
four  and  six-tenths  pounds  are  recovered  in  the  whey. 

The  solid  matter  in  the  cheese  is  composed  mainly  of 
fat  and  casein.  When  the  fat  in  the  milk  is  increased, 
the  amount  of  fat  in  the  cheese  is  also  proportionally  in- 
creased. With  poor  making  this  increase  of  fat  in  the 
milk  may  very  easily  be  lost. 

The  following  types  of  milk  are  given  to  show  where 
the  various  constituents  of  milk  go  in  the  process  of 
cheese-making  : 

EXAMPI.E  No.  I. 

100  From  roo  pounds  of  milk, 

pounds  Loss  in  Recovered 

milk.  whey.  in  cheese. 

Water,    lbs 87.52  80.97  3.65 

Solids      "   12.48  6.23  6.25 

Ash          "   0.80  0.52  0.28 

Fat           "   3.50  0.30  3.20 

Casein  and  albumin,  lbs-     3.22  0.84  2.38 

Milk  sugar,  lbs 4.80  4.35 

Example  No.  2. 

Water,    lbs 86.79  8^^.89  3.59 

Solids      "    13.21  6. II  7. II 

Ash  "   0.64  0.40  0.24 

Fat  "    4.00  0.34  3.66 

Casein  and  albumin,  lbs.     3.71  0.81  2.90 

Milk  sugar,  lbs 4.50  4.30 


MII.K   SOIvIDS   IN    CHKKSK-MAKING.  67 

M11.K  WITH  Cream  Added. 

Water,    lbs 85.87  76.01  4.56 

Solids      "   14.13  5.69  8.44 

Ash          '*   0.77  0.42  0.35 

Fat           "   6.00  0.49  5,51 

Casein  and  albumin,  lbs-  3.12  0.52  2.60 

Milk  sugar,  lbs 4.13  4.00 

Skimmed  Mii,k. 

Water,    lbs 87.80  80.80  3.00 

Solids      "   12.20  6.19  6.01 

Ash          "   0.80  0.31  0.49 

Fat           "   2.75  0.34  2.41 

Casein  and  albumin,  lbs-  3.95  0.82  3.13 

Milk  sugar,  lbs 4.55  4.45 

The  amount  of  cheese  that  can  be  made  from  loo 
pounds  of  milk  depends  upon  (i)  the  skill  of  the  maker, 
(2)  the  amount  of  water  left  in  the  cheese,  and  (3)  the 
composition  of  the  milk  used,  The  richer  a  milk  in  fat 
the  greater  is  the  amount  of  cheese  produced  per  pound 
of  milk.  Experiments  illustrating  this  point  are  to  be 
found  in  Bulletin  No.  19,  Minnesota  Experiment  Station, 
from  which  the  following  is  taken  : 

Pounds  milk  to        Fat  recovered 
Range  of  fat.  make  pounds  in  cheese. 

No.  of  trials.  Per  cent.  cheese.  Per  cent. 

28  3-5— 4-0  9.68  91.69 

31  4.1—4.6  9.30  92.77 

14  4-7— 5.1  8.90  92.86 

4  5.1—6.0  8.56  94.46 

Composition  of  Cheese  Made  from  Different  Mii,ks. 

No.  I.  No.  2.          No.  3.  No.  4. 

3.50  4.00  Creamed  Skim-milk. 

per  cent,  per  cent.       milk.  Per 

fat  fat.  Per  cent.  cent. 

Water 34.29  31.4        32.43  30.68 

^at  .^ 33.76  35.3         43.55  27.09 

Casein  and  albumin.  24.47  27.7        20.00  36.00 


68  THE    CHEMISTRY   OF   DAIRYING. 

Observe  that  in  a  cheese  made  from  normal  milk  the 
amount  of  fat  always  exceeds  the  amount  of  casein  and 
albumin.  In  the  case  of  the  skim-milk,  when  only  a 
small  part  of  the  fat  is  removed  from  the  milk,  it  is  to 
be  observed  that  the  fat  in  the  cheese  is  then  less  than 
the  casein  and  albumin.  Hence  the  difference  in  com- 
position between  whole-milk  and  skim-milk  cheese :  the 
per  cent,  of  casein  is  less  than  the  fats  in  whole-milk 
cheese,  while  in  skim-milk  cheese  the  percent,  of  casein 
is  greater  than  the  fat. 

The  richness  of  a  sample  of  cheese  in  butter-fat  can 
be  approximately  determined  with  the  Babcock  test, 
aided  by  a  delicate  pair  of  scales. 

55.  Testing  Cheese  by  the  Babcock  flilk  Test. — If 
the  cheese  is  cut,  obtain  a  number  of  small  pieces  from 
different  parts  of  the  cheese.  If  it  is  not  cut,  take  four 
"plugs"  from  different  parts  of  the  cheese.  With  a 
sharp  knife  and  in  a  cool  room,  cut  the  cheese  into  small 
pieces  about  the  size  of  wheat  grains.  Then,  on  a  pair 
of  well-balanced  scales,  weigh  out  five  grams  of  cheese. 
In  the  absence  of  gram  weights,  use  a  five-cent  piece 
which  weighs  just  five  grams.  Then  introduce  the  five 
grams  of  well  mixed  cheese  sample  into  a  test-bottle  by 
means  of  a  paper  funnel.  Add  about  ten  or  twelve  cc. 
of  hot  water,  and  shake  well  so  as  to  thoroughly  break 
down  the  cheese.  Add  a  little  more  water,  five  cc,  and 
mix.  Complete  the  test  in  the  usual  way  as  for  milk 
testing. 

In  order  to  get  the  per  cent,  of  fat  in  the  cheese,  it  is 
necessary  to  multiply  the  per  cent,  of  fat  found  b}^  the 


THE   RIPENING   OF   CHEESE.  69 

test  by  3.6,  because  the  test-bottles  are  graduated  for 
eighteen  grams  and  only  five  grams  have  been  used.  If 
the  per  cent,  of  fat  in  the  cheese  falls  much  below  thirty- 
two  per  cent.,  the  cheese  has  not  been  made  from  nor- 
mal milk. 

56.  Testing  Whey. — In  the  making  of  cheese,  both  the 

whey  and  the  drippings  from  the  cheese  press  should  be 
frequently  tested  for  fat  so  as  to  determine  whether  there 
has  been  any  unnecessary  loss  of  fat.  In  testing  whey, 
the  special  bottles  made  for  testing  skim-milk  may  be 
used.  It  is  not  necessary  to  use  17.6  cc.  of  acid  because 
the  casein  has  been  removed  from  the  milk,  and  the 
acid  has  less  work  to  do.     Use  about  eight  cc.  of  acid. 

57.  The  Ripening  of  Cheese  is  a  continuation  of  the 
digestion  process  which  was  started  in  the  vat  by  the 
rennet  ferments.  The  length  of  time  required  for  curing, 
and  before  the  cheese  is  read}-  for  market,  ranges  from 
two  months  to  a  year  or  more,  depending  upon  the  con- 
ditions of  making  and  curing. 

Factors  Which  Produce  a  Long-Keeping  Cheese. 

1.  Rennet  test  showing  milk  to  be  only  moderately  ripe.  Ren- 
net test  50  to  60. 

2.  Smaller  quantity  of  rennet  and  lower  temperature  of  milk. 

3.  Hot  iron  test,  short  threads. 

4.  Heavy  salting. 

5.  Heavy  pressing. 

6.  Lower  temperature  of  curing-room  and  lower  temperature 
for  ripening. 


70  THE    CHEMISTRY   OF    DAIRYING. 

Factors  Which  Produce  a  Quick-Ripening  and  Eari.y 
Market  Cheese. 

1.  Rennet  test  showing  milk  to  be  over-ripe.  Rennet  test  45 
to  50. 

2.  Large  quantity  of  rennet  and  higher  temperature  of  milk. 

3.  Hot  iron  test,  long  threads. 

4.  Light  salting. 

5.  Moderate  pressing. 

6.  Higher  temperature  of  curing-room  and  more  rapid  ripen- 
ing. 

In  making  cheese  it  is  sometimes  necessary  to  balance 
these  factors.  An  over- ripe  milk  may  be  given  some 
of  the  treatment  for  producing  a  long-keeping  cheese, 
such  as  hea\^"  salting  and  slow  curing,  which  will  neu- 
tralize the  effects  of  the  over-ripe  milk. 

When  a  milk  is  rich  in  fat,  a  larger  quantity  of  rennet 
is  used  and  the  milk  is  set  at  a  higher  temperature. 

The  two  most  essential  conditions  for  curing  cheese 
are :  uniform  temperature  and  a  certain  amount 
moisture  in  the  air.  All  fermentation  actions  are  the 
most  complete  when  the  range  of  temperature  is  between 
narrow  limits.  A  high  temperature  is  unfavorable  to 
some  of  the  ferments.  Sudden  changes  in  temperature 
destroy  the  vitality  of  the  ferments. 

The  atmosphere  of  the  curing-room  should  contain 
from  eighty  to  ninety-five  per  cent,  of  water.  The  amount 
of  water  in  the  air  is  determined  by  the  hygrometer, 
which  is  easily  made.  Two  thermometers  are  fastened 
to  a  board.  One  is  known  as  the  dry  bulb  thermometer, 
the  other  one  as  the  wet  bulb  thermometer.     A  piece  of 


THE   RIPENING   OF    CHEESE. 


71 


woolen  cloth,  c,  wrapped  around 
the  bulb  of  the  thermometer  leads 
to  the  cup  of  water,  w.  The  cloth 
is  kept  wet  by  capillarity.  When 
the  air  is  saturated  with  water,  the 
dry  bulb  and  wet  bulb  thermome- 
ter readings  are  the  same.  When 
the  air  is  not  saturated,  the  wet  bulb 
thermometer  shows  a  lower  tem- 
perature. The  greater  the  differ- 
ence in  temperature  between  the 
two  thermometers,  the  smaller  the 
amount  of  moisture  in  the  air.  The 
amount  of  water  in  the  air  is  deter- 
mined from  the  table. 


Fig.  18. 


Difference  be- 

Dry bulb 

tween  the  two 

Percent 

thermometer. 

thermometers. 

moisture. 

55° 

0 

100 

55 

I 

93 

55 

3 

81 

55 

5 

67 

60 

I 

93 

60 

3 

83 

60 

5 

70 

65 

I 

94 

65 

3 

84 

65 

5 

73 

70 

I 

94 

70 

3 

85 

70 

5 

74 

75 

I 

95 

75 

3 

86 

75 

5 

75 

72  THE    CHEMISTRY   OF    DAIRYING. 

There  should  never  be  a  greater  difference  than  3°  be- 
tween the  dry  bulb  and  wet  bulb  thermometer  readings. 
Before  taking  the  wet  bulb  reading,  fan  away  the  air 
from  around  the  thermometer  and  bulb,  because  the  air 
near  the  thermometer  may  not  be  the  same  as  the  air  of 
the  room. 

58.  Paying  for  flilk  by  Test  in  Cheese  Factories. — 
The  paying  for  milk  on  the  basis  of  the  fat  which  it  con- 
tains, as  determined  by  the  test,  is  more  accurate  than 
the  usual  way  of  paying  by  weight.  When  the  milk 
tests  between  three  and  four-tenths,  and  four  and  one- 
tenth  per  cent,  fat,  the  amount  of  cheese  made  from  the 
milk  is  practically  proportional  to  the  amount  of  fat 
present  in  the  milk.  Inasmuch  as  average  milk  tests 
between  these  two  points,  the  test  can  be  used,  because 
the  butter  value  and  the  cheese  value  of  the  milk  are  prac- 
tically the  same.  When  the  milk  is  poor  in  fat,  a  pound 
of  milk  fat  produces  more  cheese. 

The  richer  milks  produce,  asarule,  better  cheese  which 
commands  a  higher  price  than  the  cheese  made  from 
poorer  milks.  One  pound  of  milk  fat  will  make,  on  the 
average,  about  two  and  six-tenths  pounds  of  cured 
cheese,  depending  upon  the  richness  of  the  milk  in  fats. 

When  the  milk  tests  One  pound  of  fat  makes 

3.2  per  cent,  fat  2.8  pounds  cheese. 

3-4    "       "       "  2.7        - 

3.6    "       "       "  2.6 

3.8    "       "       "  2.6 

4.1    "       ''       "  2.5 

4.5    "       "       "  C4 
The  fat  test  should  be  used  in  cheese  factories  for  the 


COMPARATIVE  AMOUNTS  OF  BUTTER  AND  CHEESE.    73 

making  out  of  the  dividends,  the  same  as  in  the  cream- 
ery. In  order  to  calculate  approximately  the  amount  of 
cheese  that  can  be  made  from  a  certain  amount  of  milk, 
it  is  first  necessary  to  determine  the  total  fat  in  the  milk 
and  then  to  multiply  by  the  amount  of  cheese  that  can 
be  made  from  one  pound  of  fat  of  that  kind  of  milk. 

Exercise. — 5000  pounds  milk  testing  3.6  per  cent,  fat  =  5000 
X  0.036  =  180  pounds  fat.  As :  i  pound  of  fat  in  3.6  per  cent, 
milk  will  make  2.6  pounds  cheese;  hence,  180  X  2.6  =  468  pounds 
of  cheese  produced  from  5000  pounds  of  3.6  per  cent.  milk. 

59.  Comparative  Amounts  of  Butter  and  Cheese 
riade  from  the  Same  Milk. — Using  this  as  an  example, 
it  is  an  easy  matter  to  calculate  the  comparative  gross 
proceeds  from  the  sale  of  cheese  and  butter,  at  current 
market  prices. 

As  a  rule,  one  pound  of  fat  will  make  about  a  sixth  of 
its  weight  more  of  butter,  because  of  the  water  which  is 
added  to  it  in  making.  In  order  to  get  the  butter 
equivalent  from  the  total  fat,  add  one-sixth  to  the  weight 
of  fat  taken,  as  :  180-^6  =  30;  180  +  30=  210  ;  or  180 
pounds  of  fat  will  produce  about  210  pounds  of  butter. 
If  the  butter  sells  at  eighteen  cents  and  cheese  at  eight 
cents  per  pound,  the  gross  proceeds  from  the  butter 
will  be  $37.80  and  from  the  cheese  $37.44. 

Instead  of  using  the  factors  as  given  here,  the  cheese- 
maker  or  the  butter-maker  should  use  the  factors  ob- 
tained from  his  own  work.  A  butter-maker  finds  from 
his  records  that 

One  week,  484  pounds  fat  by  test  make  581  pounds  butter. 
«.        "       612         "         "     "     "       "        732        "  <* 

"        -       316        "         -     "     -       "        370       - 
Then  512         "         "     **     "  should  make  ?  " 


74  THE    CHEMISTRY   OF   DAIRYING. 

In  three  weeks  141 2  pounds  of  fat  produced  1683 
pounds  butter,  or  one  pound  of  fat  produced  1.19  pounds 
butter,  or  one  pound  of  butter  is  made  from  0.83  pound 
of  fat.  The  512  pounds  of  fat  would  then  make  about 
609  pounds  of  butter. 

In  making  out  the  dividends  in  either  the  cheese  fac- 
tory or  the  creamery,  the  calculations  should  all  be  made 
entirely  upon  the  basis  of  the  total  fat  and  the  net  pro- 
ceeds. The  total  amount  of  fat  found  by  test  is  sold  in 
the  form  of  butter  or  cheese  for  a  certain  sum  of  money. 
After  deducting  the  cost  of  making,  etc.,  the  net  receipts 
for  so  many  pounds  of  fat  are  to  be  divided  among  the 
patrons  according  to  the  amount  of  fat  which  they  have 
brought  to  the  factory  or  creamery. 

Every  pound  of  fat  found  by  test  is  then  worth  a  cer- 
tain amount  of  money. 

Exercise. — Make  out  the  following  dividends,  first  on  the  basis 
of  the  total  fat,  and  second,  by  the  total  weight  only. 

Pounds  Fat  found  Dividend. 

Patron.  milk.  by  test.  Test-  Weight. 

1  1512  4.0  

2  1700  3.6  

3  1200  4.8  • 

4  2100  3.4  

5  1400  4.5  


370  pounds  of  butter  are  produced.     The  butter  is  sold   for 
eighteen  cents  per  pound.     Cost  of  making,  etc.,  I7.50. 


REFERENCES  TO  CHAPTER  VII. 

1.  The  Proteids  of  Milk.     Hammarsten. 

2.  The  Albumin,  Peptin,   Galactin,  etc.,   are  Other  Forms  of 
Casein.     Duclaux  :  Comptes  rendus,  1884,  4,  98. 


REFERENCES   TO   CHAPTER    VII.  75 

3.  The  Content  of  Pepton  in  Milk.  Schmidt  and  Miilheim  :  Re- 
ported in  Konig,  Chemie  der  Menschlichen  Nahruugs-und  Ge- 
nussmittel,  Band  II. 

4.  The  Proteids  of  Milk.    Halliburton  :  Journal  of  Physiology, 

2,  459- 

5.  The  Chemistry  of  Casein  and  the  Theory  of  the  Curdling 
Action  of  Rennet.  G.  Courant :  Abstract  in  Experiment  Station 
Record,  5. 

6.  Three  Forms  of  the  Casein  in  Milk.  Struve  :  Journal  fiir 
practische  Chemie,  1884. 

7.  The  Action  of  Rennet  on  Milk.  Hammarsten:  Popular  Form 
given  in  Milk,  its  Nature  and  Composition  by  Aikman, 

8.  The  Curdling  of  Milk  by  Ferments  which  Render  the  Milk 
Alkaline.  Warrington  :  Journal  of  the  Chemical  Society  (Eng- 
land), 1888. 

9.  A  Study  of  the  Coagulating  Power  of  Commercial  Rennets. 
Patrick  :  Abstract  in  Experiment  Station  Record,  5,  100. 

10.  The  Isolation  of  Rennet  from  Bacteria  Cultures.  Conn  : 
Connecticut  (Storr's)  Experiment  Station,  Fifth  Annual  Report. 

11.  The  Nature  of  Rennet.  Russell:  Outlines  of  Dairy  Bac- 
teriology. 

12.  Beitrage  zur  Erfarschung  der  Kaserifange.  Baumann  : 
Die  I^andwirtschaftlichen  Versuchs-Stationen,  42,  et  seq. 

13.  Cheese-Making,  Directions  for.  Iowa  Experiment  Station, 
Bulletins  Nos.  19  and  21. 

14.  Cheese  Factory  Notes.  Wisconsin  Experiment  Station, 
Annual  Report,  1892. 

15.  Cheese-Making.  Article  Relating  to  Recent  Work  on 
Dairying.  Allen:  Experiment  Station  Record,  5.    No.  10  and  11. 

16.  Cheddar  Cheese-Making.     Decker. 

17.  A.  B.  C.  in  Cheese-Making.     Monrad. 

18.  Cheese-Making  in  Switzerland.     Monrad. 

19.  The  Manufacture  and  Production  of  Cheese.  Alvord  : 
United  States  Department  of  Agriculture,  Year  Book,  1895. 

20.  The  Manufacture  of  Some  Fancy  Brands  of  Cheese.  Lusch- 
inger :  Report  Sixteenth  Annual  Convention  of  the  Minnesota 
Dairy  Association. 


76  THE    CHEMISTRY    OF    DAIRYING. 

21.  Manufacture  of  Sweet  Curd  Cheese.  Haecker  :  Minnesota 
Experiment  Station.    Bulletin  No.  35. 

22.  Experiments  in  Cheese-Making.  Minnesota  Experiment 
Station,  Bulletin,  No.  19. 

23.  Cheese-Making,  Distribution  of  Ingredients,  and  Losses  of 
Fat.     Handbook  of  Experiment  Station  Work. 

24.  Losses  in  Cheese-Making.  Vermont  Experiment  Station, 
Fifth  Annual  Report. 

25.  Experiments  in  the  Manufacture  of  Cheese.  New  York 
State  Experiment  Station.     Bulletins  No.  37,  43,  45,  46,  and  56. 

26.  Experiments  in  Cheese-Making.  Ontario  Agricultural 
College  Report,  1894. 

27.  Losses  of  Milk  vSolids  in  Cheese-Making,  and  the  Addition 
of  Cream  to  the  Milk.  Minnesota  Experiment  Station,  Bulletin 
No.  19. 

28.  Investigations  Relating  to  the  Manufacture  of  Cheese.  New 
York  State  Experiment  Station,  Bulletin  No.  65. 

29.  Determining  the  Amount  of  Fat  {n  Cheese  by  the  Babcock 
Test.     Wisconsin  Experiment  Station,  Bulletin  No.  36. 

30.  Composition  of  Different  Kinds  of  Cheese  Made  in  Differ- 
ent Countries.  Konig  :  Chemie  der  Menschlichen  und  Genuss- 
mittel.     Band  II. 

31.  The  Composition  of  English  Cream  Cheese.  (Cream  added 
to  the  Milk.)     P.  Vieth  :  Milch  Zeitung,  1887,   120. 

32.  The  Composition  of  Milk,  Cheese,  and  Whey  in  Relation 
to  One  Another.     Ontario  Agricultural  College  Report,  1894. 

33.  The  Composition  of  Cheese  Made  from  Cream.  Hassall : 
Foods,  Adulterations  and  the  Methods  for  their  Detection. 

34.  The  Composition  of  Cheese.  Connecticut  State  Experi- 
ment Station  Report,  1892. 

35.  Ripening  of  Cheese.  Adametz  :  Berlin.  Landwirtschaft- 
licher  Jahrbiicher,  1889. 

36.  The  Abnormal  Ripening  of  Cheese.  Adametz:  Milch  Zeit- 
ung, Nos.  21  and  22,  1892  and  1893. 

37.  An  Aromatic  Bacillus  in  Cheese.  Iowa  Experiment  Sta- 
tion, Bulletin  No.  21. 


REFERENCES  TO   CHAPTER   VII.  77 

38.  The  Changes  during  the  Ripening  of  Cheese.  Iowa  Ex- 
periment Station,  Bulletin  No.  24. 

39.  Salt  and  Its  Preventing  the  Swelling  of  Cheese.  Von  Freu- 
denreich  :  Abstract  in  Experiment  Station  Record,  vol.  v,  p.  921. 

40.  The  Forms  of  the  Nitrogen  Compounds  in  Cheese.  Stut- 
zer :  Reported  in  Wiley's  Agricultural  Analysis,  vol.  iii. 

41.  Fat  in  Milk  as  a  Practical  Basis  for  Determining  the  Value 
of  Milk  for  Cheese-Making.  New  York  State  Experiment  Sta- 
tion, Bulletin  No.  68. 

42.  The  Use  of  the  Hygrometer  in  Cheese-Curing  Rooms.  New 
York  State  Experiment  Station,  Bulletin  No.  56. 

43.  Hygrometer  for  Cheese  Cellar.     Molkerei  Zeitung,  No.  34. 

44.  Milk  Fat  and  Cheese  Yield.  New  York  State  Experiment 
Station,  Bulletin  No.  no. 


CHAPTER  VIII. 
Ash  and  Miscellaneous  Compounds  in  Milk. 

60.  Ash  of  Milk. — The  ash  of  milk,  as  previously 
stated,  is  that  portion  of  the  milk  solids  which  cannot  be 
converted  into  smoke  or  volatile  products  b}^  burning. 
The  fat,  casein  and  milk  sugar  are  substances  that  will 
burn,  and  they  are  called  organic  compounds,  while  the 
ash,  which  is  the  product  left  from  burning,  is  called  the 
mineral  or  inorganic  portion. 

One  hundred  pounds  of  milk  will  yield  about  0.75  of  a 
pound  of  ash,  which  is  composed  of : 

Per  cent. 

Potash 21. II 

Soda 8.08 

Lime 24-19 

Magnesia    2-57 

Iron  oxide 0.34 

Phosphoric  acid 32-11 

Sulphuric  acid 2- 16 

Chlorine 8-51 

The  most  abundant  compounds  in  the  ash  of  milk  are  : 
Phosphates  of  lime,  potash  and  common  salt. 

The  ash  of  milk  supplies  materials  for  bone  growth, 
such  as  bone  phosphate  of  lime. 

61.  Citric  Acid  in  Milk. — In  milk,  the  lime  is  com- 
bined largely  with  citric  acid  and  forms  citrate  of  lime. 
Citric  acid  is  the  same  acid  or  sour  principle  found  in 
lemons.     The  taste  of  citric  acid  in  milk  is  not  observed 


COI.OSTRUM   MIIvK.  79 

because  of  its  combination  with  the  calcium.  There  is 
about  one-tenth  per  cent,  of  citric  acid  in  milk.  About 
as  much  citric  acid  as  is  found  in  a  good-sized  lemon, 
is  present  in  a  quart  of  milk.  The  presence  of  this  acid 
in  milk  was  recently  discovered  by  Henkel.  How  it  is 
produced  and  the  part  it  takes  in  dairy  operations  are 
not  known. 

62.  Colostrum  Hilk. — The  milk  given  by  a  cow  for 
the  first  three  or  four  days  after  calving  is  quite  different 
in  color,  taste,  and  appearance  from  milk  in  its  normal 
condition.  Such  milk  is  called  colostrum  milk,  and  has 
a  different  chemical  composition  from  ordinary  milk. 
Colostrum  milk  has  a  yellow  color  and  a  sweetish  taste 
and  a  characteristic  oily  feeling.  It  coagulates  on  boiling 
on  account  of  the  large  amount  of  albumin  which  is 
present.  Pour  hot  water  into  colostrum  milk  and  it 
curdles.  Colostrum  milk  has  a  higher  specific  gravity 
than  normal  milk,  frequently  reaching  1.064. 
Composition  of  Coi^ostrum  Mii.k.^ 

Per  cent. 

Water  71 -SO 

Solids 28.50 

Solids  contain : 

Per  cent. 

Fat 6 .  04 

Casein 3-50 

Albumin 12.67 

Sugar 4-85 

Ash 1-35 

Undetermined o-09 

28.50 

1  Analysis  made  by  the  author. 


8o  THE    CHEMISTRY    OF    DAIRYING. 

•  The  term  colostrum  is  used  because  of  the  presence  of 
circular  bodies  in  the  milk,  larger  than  the  fat  globules, 
and  known  as  colostrum  cells.  These  colostrum  cells 
are  similar  in  structure  to  white  blood  corpuscles,  from 
whence  it  is  supposed  they  are  derived.  When  exam- 
ined under  the  microscope,  while  the  milk  is  still  warm, 
they  will  produce  the  amoeboid  movement,  common  to 
white  blood  corpuscles. 

These  colostrum  cells  begin  to  make  their  appearance 
in  milk  about  a  week  before  the  calf  is  born.  Four  or 
five  days  after  calving  the  albumin  decreases  and  the 
milk  gradually  reaches  its  normal  condition.  The  colos- 
trum acts  as  a  purge  upon  the  young  calf. 

The  creaming  of  colostrum  milk  is  very  imperfect  on 
account  of  the  albumin  which  is  present  in  such  large 
quantities.  Colostrum  milk  should  never  be  mixed  with 
other  milk,  because  it  will  prevent  creaming  by  clogging 
the  separator  as  well  as  produce  an  inferior  product. 

In  cheese-making,  colostrum  seriously  interferes  with 
the  curing  and  keeping  qualities  of  the  cheese.  Colos- 
trum is  not  so  objectionable,  for  sanitary  reasons,  as  it 
is  on  account  of  its  affecting  the  quality  of  the  products. 

63.  Tyrotoxicon  is  a  poisonous  chemical  compound 
which  is  sometimes  found  in  stale  milk  and  old  cheese. 
Thetj^rotoxicon,  when  separated  and  examined  with  the 
microscope,  appears  in  long  needle-shaped  crystals. 
This  poisonous  compound  is  produced  by  bacteria,  and 
is  a  ptomaine,  or  poisonous  compound  formed  from  de- 
composing animal  matter.  When  tyrotoxicon  is  present 
in    milk    in    small    quantities    it   produces     diarrhoea, 


Colostrum  Chlls  in  Cow's  :Milk        x  300. 


Detached  Membranes  in  Colostrum  Milk        x  150. 


FIBRIN    IN    MIIvK.  8l 

and  symptoms  similar  to  those  of  cholera.  It  proves 
fatal  when  injected  into  the  veins  of  small  animals.  This 
is  the  material  which  causes  the  trouble  from  eating 
old  cheese.  It  is  most  apt  to  be  present  in  the  rind. 
The  tyrotoxicon  is  sometimes  developed  in  ice-cream. 
When  the  cream  becomes  old  and  when  gelatin  is  used 
the  conditions  are  favorable  for  its  formation.  The  so- 
called  ice-cream  poisoning  is  due  to  this  compound. 

Inasmuch  as  this  material  is  produced  by  bacteria 
which  feed  upon  decomposing  products,  the  utmost 
cleanliness  is  absolutely  necessary  to  prevent  its  form- 
ing. It  is  the  tyrotoxicon  which  causes  the  scouring  of 
calves  and  pigs.  Hence,  keep  the  whey  and  skim-milk 
barrels  clean. 

64.  Urea  in  Milk. — When  muscular  tissues  of  the 
body  are  broken  down,  a  part  of  the  waste  materials  are 
separated  and  carried  off  by  the  kidneys,  in  the  form  of 
urea,  a  white  crystalline  compound  dissolved  in  the 
urine.  There  are  traces  of  this  compound  in  nearly  all 
of  the  fluids  of  the  body.  It  is  present  in  milk  to  the 
extent  of  0.001  per  cent.,  and  anymore  than  this  amount 
is  due  to  some  diseased  condition  of  the  animal. 

65.  Fibrin  in  Milk. — Another  nitrogenous  compound, 
present  in  milk,  is  fibrin,  the  compound  present  in 
blood  which  forms  the  "clot."  The  best  proof  of  the 
presence  of  fibrin  in  milk  is  the  microscopic  appear- 
ance of  the  fat  globules.  It  has  previousl}-  been  stated 
that  the  fat  globules  always  appear  in  little  groups 
or  colonies.  It  is  supposed  that  the  globules  are 
held  together  by  the  bands  or  meshes  of  fibrin  and  are 


82  THE    CHEMISTRY    OF    DAIRYING. 

thus  prevented  from  coming  to  the  surface  in  the  grav- 
ity creaming  process.  The  amount  of  fibrin  in  milk 
is  about  the  same  as  that  of  urea,  o.ooi  to  o.oooi  per  cent. 
Fibrin  is  produced  by  the  action  of  the  fibrin  ferment. 
The  chemical  proofs  for  the  determination  or  even 
the  detection  of  its  presence  in  milk,  are  very  unsatisfac- 
tory. In  Bulletin  No.  29,  Cornell  Experiment  Station, 
it  appears  from  the  tests  that  the  amount  of  fibrin  in 
milk  from  cows  advanced  in  their  lactation  period  is  not 
related  or  proportional  to  the  thoroughness  of  the 
creaming  of  milk  by  the  gravity  process. 

66.  Gases  in  flilk. — The  gases  which  are  dissolved  in 
milk  as  it  comes  from  the  cow  are  :  Nitrogen,  oxygen, 
and  a  small  amount  of  carbon  dioxide.  The  nitrogen 
and  oxygen  are  dissolved  in  the  milk  in  about  the  same 
proportion  as  in  pure  spring  water.  When  milk  gets 
older,  the  oxygen  in  the  milk  decreases  and  the  carbon 
dioxide  increases.  The  carbon  dioxide  is  the  same  gas 
that  is  given  off  in  respired  air ;  the  ox3-gen  in  the  milk 
has  been  used  up  to  form  carbon  dioxide. 

At  the  end  of  four  or  five  da3'S  ninety  per  cent,  of  the 
gas  in  milk  will  be  carbon  dioxide.  There  is  always 
more  gas  in  old  than  there  is  in  fresh  milk.  When  the 
milk  becomes  saturated  with  gas,  the  gas  is  given  off. 
When  the  gas  escapes  from  the  surface  of  cream  or  thick 
milk,  it  leaves  small  holes  on  the  surface.  When  milk 
or  a  starter  shows  these  openings,  sometimes  called 
"eyes  "  by  the  cheese-maker,  it  wnll cause  much  trouble 
if  used  for  cheese-making. 

In  addition  to  carbon  dioxide,  other  gases  of  a  differ- 


BUTTER    COI.ORS.  83 

ent  character  may  be  present  in  milk  and  cause  the  curd 
to  float  :  such  as  hydrogen,  which  is  given  off  in  butyric 
acid  fermentation,  and  also  derivatives  of  tne  marsh  gas 
series  of  gases. 

The  gases  in  milk  are  a  part  of  the  products  produced 
by  bacteria,  and  hence  the  milk  may  cause  trouble,  not 
only  from  the  gases  present,  but  also  from  the  bacteria. 

67.  The  Color  of  flilk. — The  color  of  milk  is  imparted 
by  a  chemical  compound,  and  is  not  due  to  either  a  high 
or  low  per  cent,  of  fat.  The  coloring  matter  which  im- 
parts to  milk  its  yellow  color  and  also  gives  the  color  to 
butter,  whey,  etc.,  is  a  nitrogenous  compound  called,  by 
Blyth,  lactocrome.  The  amount  of  this  coloring  matter 
is  influenced  by  the  food  consumed  and  also  by  the 
special  peculiarities  of  the  cow.  There  is  a  marked  dif- 
ference in  the  color  of  milks  from  cows  fed  on  the  same 
food.  Frequently  a  yellow  tinged  milk  will  show  a 
smaller  per  cent,  of  fat  than  a  milk  of  a  lighter  shade. 

Milk  dealers  sometimes  take  advantage  of  the  popular 
idea  in  regard  to  the  color  of  milk  as  indicating  a  rich 
milk,  and  add  a  little  annatto  or  other  coloring  matter  to 
impart  the  desired  yellow  tinge. 

Butter  colors  are  nearly  all  made  from  the  seeds 
of  Bixa  Orellana  and  are  harmless  vegetable  materials. 
The  use  of  butter  colors  does  not  come  under  the  head  of 
adulterating  butter,  because  the  natural  color  of  butter  is 
yellow  and  butter  without  this  color  is  unnatural  butter. 
The  public  demands  a  uniform  color,  hence,  in  certain 
seasons  of  the  year,  when  butter  does  not  possess  the  req- 


84  THE    CHEMISTRY   OF   DAIRYING. 

uisite  color,   it  is  considered   justifiable  to  use  butter 
colors. 


REFERENCES  TO  CHAPTER  VIII. 

1.  Composition  of  the  Ash  of  Milk.     Maine  Experiment  Sta- 
tion Report,  1890. 

2.  Milk  Ash  Analysis.     New  Hampshire  Experiment  Station 
Report,  1888. 

3.  Average  Composition  of  Milk  Ash.    Konig  :  Chemische  der 
menschlichen  Nahrungs  und  Genussmittel.     Band  II. 

4.  The   Phosphates   of   Milk.      Duclaux  :  Annals  Pasteur  In- 
stitute, 1893. 

5.  Calcium  Phosphate  and   the  Casein.     Soldner  :    Die  Land- 
wirtschaftlichen  Versuchs-Stationen,  1888,  35. 

6.  Citric  Acid  as  a  Normal  Constituent  of  Cow's  Milk.     Hen- 
kel :  Die  Landwirtschaftlichen  Versuchs-Stationen,  39. 

7.  Citric  Acid  in  Milk.     Abstract.     Sixth  Annual  Convention 
(1889),  Association  of  Official  Agricultural  Chemists. 

8.  The  Composition,  Creaming,  and  Churning  of  Colostrum. 
Vermont  Experiment  Station,  Fifth  Annual  Report. 

9.  Composition  of  Colostrum  Milk.     Kruger :  Molkerei  Zeit- 
ung,  1892. 

TO.  The  Chemical  Composition  of  Cow's   Colostrum.     Blyth  : 
Foods,  their  Composition  and  Analysis. 

11.  Nature  of  the  Colostrum  Cells.     Heidenhain  :  Handbuch 
der  Physiologie. 

12.  Tyrotoxicon.     Vaughan  :  Michigan  State  Board  of  Health 
Report,  1886. 

13.  The  Chemistry  of  Tyrotoxicon,  and  its  Action  on  Lower 
Animals.     Vaughan  :  Analyst,  13,  141. 

14.  Fibrin  in  Milk.     Proceedings  of  the  Society  for  the  Promo- 
tion of  Agricultural  Science,  1888. 

15.  Fibrin  in  Milk,  and  its  Effects  upon  Creaming.    Wisconsin 
Experiment  Station,  Bulletin  No.  18. 


REFERENCES  TO  CHAPTER  VIII.  85 

16.  The  Relation  of  Fibrin  and  the  Gravity  Creaming  of  Milk. 
Cornell  University  Experiment  Station,  Bulletin  No.  29. 

17.  Gases  in  Milk.    Kirchner  :  Handbuch  der  Milchwirtschaft. 

18.  Gases   in   Milk.      Blyth  :    Foods,  their  Composition  and 
Analysis. 

19.  Gas  Producing  Organism.     Baumann :  Molkerei  Zeitung, 
7,  1893- 

20.  Blue  Milk,   Red  Milk,   Brownish-red  Milk,    Bittermilk. 
Lugger :  Minnesota  Experiment  Station,  Annual  Report,  1893. 

21.  The  Yellow  Coloring   Matter  of  Milk.      Blyth  :    Foods, 
their  Composition  and  Analysis. 


CHAPTER  IX. 

Dairy  Salt   and  Commercial   Problems  Relating  to 

Milk. 
68.  Dairy  Salt. — There  is  great  difference  in  the 
quality  of  dair}'  salt,  due  both  to  a  difference  in  chem- 
ical composition  and  to  the  physical  properties  of  the 
salt.  The  salt  particles  range  in  size  from  large  blocks, 
known  as  rock-salt,  to  a  fine  powder  that  gives  a  smooth 
surface  when  a  knife  is  pressed  upon  it.  The  coarse 
salts  are  much  slower  in  dissolving  and  require  longer 
working  of  the  butter  to  work  in  the  salt,  which  in- 
jures the  grain  of  the  butter.  Salt  that  is  too  fine  is 
also  open  to  as  serious  objections.  If  the  butter  is 
worked  too  dry  and  a  large  amount  of  fine  salt  used,  the 
salt  will  separate  and  form  a  crust  on  the  surface  of  the 
butter. 

A  salt  that  cakes  or  beoomes  quite  moist  when  ex- 
posed to  the  air  is  not  a  good  salt  for  dairy  purposes. 
Such  a  salt  usualh^  contains  impurities  in  the  form  of 
lime  and  magnesia.  A  tablespoonful  of  salt  should  dis- 
solve in  an  ordinarj^  glass  of  water* 
when  it  is  well  stirred.  Any  insoluble 
residue  is  due  to  materials  not  salt.  When 
salt  is  examined  with  the  microscope  the 
crystals   appear  as  cubes.       Sometimes 


Fig.  19.  the  crystals  are  not  clear,  due  to  impu- 

rities in  the  brine  solutions  from  which  the  salt  was 
made. 


CHANGES    DURING   TRANSPORTATION.  87 

In  chemical  composition  salt  ranges  from  97  to  99  per 
cent.,  or  more,  pure  sodium  chloride.  Impure  salt  con- 
taining lime  or  magnesia  will  impart  an  unpleasant 
caustic  taste  to  any  dairy  product.  In  a  good  dairy 
salt  the  crystals  should  be  clear,  neither  too  coarse  nor 
too  fine,  with  a  good  taste,  and  should  show^no  tendency 
to  cake  or  to  become  moist,  and  should  be  entirely  sol- 
uble in  water. 

69.  Changes  during  Transportation. — The  effect  of 
transportation  upon  the  chemical  composition  of  milk 
has  also  been  studied.  In  court  the  question  is  fre- 
quently raised,  does  milk  change  in  composition  during 
transportation,  and  when  milk  is  peddled  in  cans  does 
the  last  purchaser  get  as  much  fat  in  his  milk  as  the 
first  purchaser? 

In  England  very  extensive  experiments  on  this  point 
have  been  made.  In  one  season  over  7,000  samples  of 
milk  were  taken  and  anaWzed  at  three  different  times  : 
(i)  before  the  milk  was  sent  out,  (2)  then  again  during 
the  delivery,  and  (3)  finally  at  the  end  of  the  route. 
In  another  season,  11,000  samples  were  taken  in  the 
same  w^ay  and  analyzed.  This  w^ork  was  performed  so 
as  to  prevent  the  drivers  from  watering  the  milk  and 
making  a  profit  for  themselves.  The  chemical  work 
was  done  by  Dr.  Vieth  in  the  interest  of  a  large  dairy 
firm.  The  average  of  each  season's  work  was  : 
Average  of  7,000  Samples. 

Milk.  Cream. 

I-    Before  starting 12.75  per  cent,  solids.  49-0  per  cent,  fat, 

2.    During  delivery.  ••  12.74         "  "  "  " 

3-    At  close 12.81         "  *'  49.1         "  " 


65  THE    CHEMISTRY    OF    DAIRYING. 

Average  of  11,000  Samples. 

1.  Before  starting 12-84  percent,  solids.     48-3  percent,  fat. 

2.  During  delivery .. .  12.88         "  "  "  " 

3.  Atclose 12.92         "  "  48.4         "  " 

The  differences  for  both  seasons  are  ver}^  small.  The 
last  milk  is  equall}^  as  rich  in  solid  matter,  including 
fat,  as  the  first  milk  sold.  If  it  were  not,  the  solids 
would  not  be  so  nearly  alike.  The  variations  are  no 
more  than  would  occur  through  loss  of  water  caused  by 
evaporation. 

At  the  Cornell  University  Station  it  was  shown  that 
when  the  milk  was  taken  from  the  can  with  a  long- 
handled  dipper,  the  milk  was  practically  of  the  same 
composition  throughout  the  entire  route.  The  excuse 
that  the  fat  separates  and  is  dipped  off  in  the  first  part  of 
the  route,  is  not  a  valid  excuse  for  poor  milk.  If  the 
milk  were  originally  unadulterated  it  would  show  itself 
to  be  unadulterated  through  the  entire  course  of  de- 
li verj^ 

70.  Effects  of  Delay  and  CooHng  upon  Creaming. — 

When  milk  is  creamed  by  the  cold  deep  setting  process 
a  little  delaj'  in  setting  the  milk  does  not  necessarily 
affect  the  creaming.  It  was  believed  at  one  time  that 
the  very  moment  the  milk  was  taken  from  the  cow  it 
should  be  hurried  off  to  the  tank.  This  undue  haste  is 
not  necessary.  With  a  small  herd,  it  is  safe  to  complete 
the  milking  and  then  put  the  cans  in  the  tank  all  at  one 
time.  A  delay  is  not  advisable  because  it  is  not  wuse  to 
let  the  milk  be  about  too  long  exposed  to  the  odors  of 
the  barn  before  putting  it  into  the  water  tank.     Experi- 


AERATING   MILK.  89 

ments  at  the  Maine  and  Cornell  Experiment  Stations 
have  shown  that  with  the  mixed  milk  of  the  entire 
herd  there  is  but  little  loss  of  fat  when  the  milk  has 
been  delayed  in  its  setting  for  a  half  to  three-quar- 
ters of  an  hour.  At  the  Wisconsin  Station  the  herd 
was  divided  into  five  lots ;  with  three  of  the  lots 
there  was  no  appreciable  effect  caused  by  a  delay, 
but  with  two  lots  a  delay  showed  a  serious  loss  of  cream- 
ing power.  When  the  milk  of  the  five  lots  was  mixed 
there  was  but  little  effect  from  a  delay  in  setting  the  milk 
in  water.  With  some  individual  cows  there  may  be  a 
loss  of  fat  when  the  milk  is  not  set  immediately,  but 
when  the  milk  of  the  entire  herd  is  considered  there  is 
much  less  danger  of  imperfect  creaming  by  a  little  de- 
lay. Unnecessary  delays  should  be  avoided,  but  undue 
haste  is  not  necessary.  With  the  centrifugal  there  is  no 
loss  of  creaming  power  following  a  delay,  provided  the 
milk  is  at  a  proper  temperature  when  separated. 

71.  Aerating  flilk  is  simply  exposing  it  in  fine  streams 
to  a  pure  atmosphere,  so  as  to  substitute  pure  air  for  the 
impure  air  and  gas  in  the  milk.  When  the  milk  is 
aerated  while  warm  it  materially  reduces  its  tempera- 
ture, and  hence  improves  its  keeping  qualities.  In  case 
milk  is  taken  to  the  factory  only  once  a  day,  aerating  is 
an  excellent  practice  in  order  to  keep  the  milk  sweet. 
It  also  improves  the  quality  for  cheese-making.  In 
butter- making  aerating  the  milk  has  not  been  extensively 
tried,  because  it  was  believed  that  any  delay  or  cooling 
of  the  milk  injured  the  creaming  qualities  ;  but,  inas- 
much as  these  factors  are  not  nearly  so  serious  as  was 


90  THE    CHEMISTRY    OF    DAIRYING. 

once  supposed,  there  is  no  particular  reason  why  aera- 
tion cannot  be  successfully  practiced  in  butter-making. 
Aerating  milk  improves  its  quality,  but  it  does  not 
make  a  bad  milk  good. 

72.  Effects  of  One  Cow's  Milk  upon  that  of  Another  in 
Creaming. — In  case  a  cow's  milk  creams  imperfectly  on 
account  of  her  being  far  along  in  the  period  of  lactation, 
the  creaming  is  frequently  improved  by  mixing  her  milk 
with  some  from  a  fresh  cow.  The  test  should  be  used 
to  detect  any  unusual  losses.  It  is  always  well  to  com- 
bine the  milk  from  different  cows,  so  that  one  milk  may 
have  a  beneficial  effect  upon  another  in  regard  to  cream- 
ing. The  milk  test  is  the  only  safe  guide  to  follow  in 
each  case. 

73.  Cream  Raising  by  Dilution. — The  effect  of  the 
addition  of  hot  and  cold  water  on  the  creaming  of  milk 
by  the  gravity  process  has  received  much  attention.  In 
the  absence  of  ice  the  use  of  water,  either  hot  or  cold, 
has  been  recommended  in  order  to  secure  more  rapid 
and  perfect  creaming.  Experiments  on  this  line,  con- 
ducted in  Germany  some  years  ago,  showed  that  the  ad- 
dition of  water,  either  hot  or  cold,  was  not  a  successful 
practice  ;  in  fact,  it  rather  prevented  perfect  creaming. 

Since  1890,  extensive  experiments  conducted  in  this 
country  have  given  the  same  results.  At  the  Cornell 
University  station  it  was  shown  that  the  addition  of 
either  hot  or  cold  water  under  any  circumstances,  was 
always  followed  by  heavy  losses  of  fat  in  the  skim-milk ; 
much  greater,  in  fact,  than  when  no  water  was  used. 


REFERENCES   TO    CHAPTER    IX.  91 

At  one  time,  the  use  of  hot  water  was  advocated, 
but  later  experiments  have  shown  it  to  be  very  objec- 
tionable. The  use  of  hot  water  is  impracticable, 
because  it  produces  a  rapidly  souring  cream  ;  in  fact, 
a  cream  that  is  over-ripe  before  it  is  skimmed,  and  the 
result  is  a  very  poor  quality  of  butter.  Furthermore, 
diluting-  milk  with  water  requires  additional  pails,  cans, 
and  vats,  which  increases  the  labor.  The  diluted 
skim-milk  is  far  less  valuable  for  food. 

74.  Effect  upon  the  Volume  of  Cream. — The  diluted 
milk  produces  a  larger  volume  of  cream  than  the  undi- 
luted milk.  But  the  cream  from  the  undiluted  milk  is 
more  concentrated  than  the  cream  from  the  diluted 
milk.  The  addition  of  water  results  in  the  production 
of  a  larger  volume  of  thinner  cream.  In  general,  it  can 
be  said  that  anything  which  interferes  with  the  normal 
creaming  of  milk  results  in  the  production  of  a  larger 
volume  of  poorer  cream. 

Hot  or  cold  water  added  to  the  milk  does  not  improve 
the  creaming  and  it  may  cause  a  serious  loss  of  fats. 
The  use  of  water  in  gravity  creaming  is  not  advisable. 

Example. — One  hundred  pounds  of  milk  undiluted  produces 
eighty  pounds  of  skim-milk  testing  0.40  per  cent,  fat,  while,  if 
diluted,  160  pounds  of  skim-milk  yields  0.30  per  cent.  fat.  Loss 
in  undiluted  skim-milk  0.32  pounds  fat,  in  diluted  0.48  pounds 
fat.  The  increased  weight  of  the  skim-milk  causes  a  greater 
total  loss  of  fat. 


REFERENCES  TO  CHAPTER  IX. 
I.  Variations  in  the  Composition  of  Milk  during  Delivery. 
Vieth :  Analyst,  1891  and  1892. 


92  THE    CHEMISTRY   OF   DAIRYING. 

2.  On  the  Raising  of  Cream  on  the  Milk  Route.  Bergmann  : 
Milch  Zeitung,  1893. 

3.  Effects  of  Transportation  upon  the  Fat  Content  of  Milk. 
Klein  :  Chemisches  Ceutralblatt,  89,  397. 

4.  Variations  in  Fat  Content  in  Milk  Served  from  Cans  to  Cus- 
tomers.    Legal  case.     Analyst,  17,  189. 

5.  Variations  in  Fat  of  Milch  Served  to  Customers  in  Dipping 
from  Cans.  Cornell  University  Experiment  Station,  Bulletin 
No.  20. 

6.  Variations  in  the  Fat  of  Milk  served  to  Customers  from  Milk 
Cans.     Ontario  Agricultural  College,  Bulletin  No.  16. 

7.  Effects  of  Delay  in  Creaming  Milk.  Maine  Experiment 
Station  Report,  1890. 

8.  Effects  of  Delayed  Setting.  Wisconsin  Experiment  Sta- 
tion, Bulletin  No.  29. 

9.  Delay  in  Setting.  See  Creaming  Article  in  Handbook  of 
Experiment  Station  Work. 

10.  Effects  of  Delay  in  Creaming  Milk.  Cornell  University 
Experiment  Station,  Bulletin  No.  29. 

11.  Creaming  and  Aerating  Milk.  Cornell  University  Exper- 
iment Station,  Bulletin  No.  39. 

12.  Aeration  of  Milk.  Vermont  Experiment  Station,  Sixth 
Annual  Report. 

13.  Aeration  of  Milk  for  Butter  Production.  Indiana  Experi- 
ment Station,  Bulletin  No.  44. 

14.  Cream  Raising  by  Dilution.  Cornell  University  Experi- 
ment Station,  Bulletins  Nos.  20  and  29. 

15.  Cream  Raising  by  Dilution.  Illinois  Experiment  Station, 
Bulletins  Nos.  12  and  18. 

16.  Cream  Raising  by  Dilution.  Vermont  Experiment  Sta- 
tion, Fourth  and  Fifth  Annual  Reports. 

17.  Cream  Raising  by  Dilution.  Indiana  Experiment  Station, 
Bulletin  No.  44. 

18.  Cream  Raising  by  Dilution.  Article,  Creaming  of  Milk  in 
Handbook  of  Experiment  Station  Work. 


CHAPTER  X. 
The  Sanitary  Condition  of  Cows'  Milk  and  the  Milk 
of  other  Domestic  Animals. 
75.  The  Sanitary  Condition  of  Milk. — The  milk  given 
by  a  diseased  cow  is  generally  different  in  composition 
from  that  of  a  healthy  cow.  Milk  should  be  fairly 
constant  in  composition.  When  the  fat,  shown  by  the 
test,  suddenly  rises  as  high  as  eight  per  cent.,  while 
usually  it  is  about  four  per  cent.,  there  is  something 
wrong  about  the  cow.  Normal  health  is  followed 
by  a  fairly  constant  composition  of  the  milk.  Limited 
variations  are  to  be  expected,  but  not  abnormal  ones. 

MlI,K  FROM  Cow  WITH   MaMMITIS.^ 

Per  cent. 

Fat 2.80 

Casein 4.02 

Albumin 0.56 

Sugar 5.54 

Ash 0.92 

Cholesterine 

Peptones 

Urea 

Note  the  low  fat  and  high  casein  and  sugar. 

MlI,K    FROM  Cow  WITH  PNEUMONIA. 

Per  cent. 

Fat 2.96 

Casein 3 .  86 

Albumin 0-44 

Sugar 3.88 

Ash 0.80 

Cholesterine 0.58 

Galactin 0.09 

Urea o-oi 

1  From  Blyth  :  Foods. 


94  'THE    CHEMISTRY    OF    DAIRYING. 

Note  the  low  fat  and  high  sugar  and  casein. 
Milk  from  Cow  with  Tuberculosis. 

Deposits  in  lungs. l-  Deposits  in  udder  1 

Per  cent.  Per  cent. 

Fat 2.77  0.49 

Casein 3 .  65  i .  2 1 

Albumin 0-87  2 .  39 

Milk  sugar 2-82  0.47 

Ash o .  87  o.  77 

Milk  from  Cow  with  Inflammation  of  Udder.^ 

Per  cent. 

Fat 1.35 

Ash 0.92 

Albumin    5.79 

Sugar 0.32 

Undetermined i .  38 

10-76 
The  microscope  is  frequently  eniplo^^ed  to  determine 
the  presence  of  foreign  matters  in  milk.  With  inflamma- 
tion of  the  udder  the  microscope  shows  pieces  of  de- 
tached membranes,  which  appear  as  small  pieces  of 
meat.  Pus  and  colostrum  cells  can  also  be  observed 
with  the  microscope.  Milk  from  unhealth}^  cows  be- 
comes sour  much  more  readily  than  healthy  milk,  when 
both  are  subjected  to  the  same  treatment.  When  milk 
sours  very  easily  and  rapidly  something  is  wrong. 

The  sanitary  condition  of  milk,  that  is,  its  quality,  is 
equally  as  important  as  its  composition.  Milk  has  fre- 
quently caused  the  spreading  of  germ  diseases,  such  as 
scarlet  fever,  diphtheria,  and  typhoid  fever.  The  germs 
of  these  diseases  find  their  way  into  the  milk,  which  is 
a  perfect  food  for  their  nourishment  and  development, 

1  From  Blyth  :  Foods. 

2  Analysis  by  author. 


THK    SANITARY    CONDITION    OF    MII,K.  95 

and  they  are  then  distributed  through  the  milk.  The 
purity  of  the  water  supply  and  the  condition  of  the 
stables  are  the  two  most  important  factors  for  the  pro- 
duction of  good  milk.  Neither  cattle  nor  other  animals 
should  be  allowed  or  compelled  to  drink  stagnant  water. 
In  fact,  no  animal  should  be  given  water  to  drink  which 
we  would  hesitate  about  drinking  ourselves.  Impure 
water  is  frequently  the  cause  of  the  production  of  un- 
wholesome milk.  In  the  analyses  of  milk,  given  on 
preceding  pages,  observe  how  the  different  samples 
vary  in  composition  from  normal  milk.  Not  only  is  the 
quality  of  milk  affected  by  disease  but  the  quantity  or 
yield  is  also  affected. 

Animals  may,  however,  be  laboring  under  a  poisonous 
or  fatal  disease  and  yet  give  apparently  wholesome  milk. 
Such  milk,  however,  will  show  the  presence  of  ptomaine 
compounds  when  it  is  given  a  careful  chemical  and 
bacteriological  examination. 

Dirt,  disease  germs,  and  many  forms  of  bacteria  from 
foul  sources  find  their  way  into  the  milk  from  the  cow's 
udder,  and  are  the  cause  of  serious  trouble  in  both  the 
cheese  factory  and  the  creamery.  In  one  case  in  partic- 
ular, noted  by  Mr.  Willard,  a  pioneer  American  cheese- 
maker,  a  factory  was  having  much  trouble  from  the 
rapid  decomposition  of  milk.  The  cause  was  traced  to 
one  herd  and  an  extended  examination  showed  that  the 
cows,  in  passing  to  and  from  the  milking  shed,  walked 
through  a  marshy  place  that  contained  much  green  pond 
scum  and  other  decomposing  matters,  particles  of  which 
adhered  to  the  udder,  dried,  and  then  fell  off  into  the 


96  THE    CHEMISTRY   OF    DAIRYING. 

milk  pails  and  fouled  the  milk.  As  soon  as  the  cows 
were  excluded  from  this  place  the  trouble  in  the  factory 
ceased. 

In  another  case,  Soxhlet  observed  that  when  milk  was 
placed  on  a  particular  shelf  in  a  milk  room,  the  milk 
soon  became  offensive  and  indicated  but3'ric  acid  fer- 
mentation. An  examination  of  the  milk  rack  showed  that 
at  some  time  a  pan  of  milk  had  been  spilled  on  the  shelf 
above  the  one  causing  this  trouble.  The  lower  side  of 
the  shelf  had  not  been  thoroughly  cleaned  ;  hence, 
whenever  a  fresh  pan  of  milk  was  placed  on  the  shelf, 
vSpores  or  seeds  fell  off  into  the  milk  from  the  shelf 
above  and  immediately  fouled  it.  These  cases  are  men- 
tioned simply  to  show  the  care  and  cleanliness  which  are 
necessar^^  in  the  handling  of  milk. 

niLK  OF  OTHER  DOflESTIC  ANIflALS. 

76.  Mare's  Milk  resembles  cowl's  milk  in  general 
characteristics,  except  that  it  is  not  quite  so  rich  in  fat 
and  is  correspondingly  poorer  in  solid  matter.  Mare's 
milk  is  subject  to  variations  in  composition,  due  to  breed 
and  individuality,  the  same  as  cow's  milk. 

Composition  of  Mare's  Milk.^ 

Per  cent. 

Water 88-49 

Fat 2.86 

Sugar 4-75 

Ash 0.55 

Casein  and  albumin 3.35 

77,  Sow's  riilk   is  quite  rich   in  casein  and  albumin 

1  Analysis  by  author. 


sheep's   MIIvK.  97 

(proteids) ,  in  fact  there  is  about  twice  as  much  of  these 
compounds  as  in  cow's  milk. 

Composition  of  Sow's  M11.K. 

Per  cent. 

Water  4.00 

Fats 4.60 

Casein  and  albumin 7 .  25 

Sugar 3.15 

Ash 1 .  05 

Sow's  milk  is  also  rich  in  mineral  matter.  When 
skim-milk  is  enriched  by  some  product,  such  as  shorts 
and  a  little  boiled  flax-seed  meal,  the  mixture  can  be 
put  together  so  as  to  have  about  the  same  composition 
as  sow's  milk. 

78.  Sheep's  Milk  is  rich  in  fat  and  casein  as  well  as 
in  ash.  It  is  one  of  the  most  concentrated  milks  given  by 
domestic  animals. 

Composition  of  Sheep's  Milk. 

Per  cent. 

Water 82  •  25 

I'at 5.30 

Casein 6.10 

Albumin    i.oo 

Milk  sugar 4-35 

Ash LOO 

If  a  lamb  is  to  be  raised  on  milk  it  demands  the  best 
milk  that  can  be  given.  Goat's  milk  resembles  sheep's 
milk  but  is  not  so  rich  in  fat  or  casein.  The  object  in 
giving  the  composition  of  these  milks  is  to  supply 
the  necessary  information  so  that  one  may  know  how  to 
substitute  one  animal's  milk  for  another. 


98  THE    CHEMISTRY   OF   DAIRYING. 

REFERENCES  TO  CHAPTER  X. 

1.  The  Composition  of  the  Milk  of  the  Mare,  Ewe,  Goat,  Sow, 
etc.  Konig :  Chemie  der  Menschlichen  und  Genussmittel, 
Band  II. 

2.  Composition  of  Mule's  Milk.  Aubert  and  Colby  :  Journal 
of  Analytical  and  Applied  Chemistry,  7,  No.  6. 

3.  The  Care  in  the  Handling  of  Milk.  Willard  :  Practical  Dairy 
Husbandry. 

4.  The  Behavior  of  Anthrax  Bacilli  in  Milk.  O.  Caro  :  Chem- 
isches  Centralblatt,  1894,  i,  164. 

5.  Behavior  of  Cholera  Germs  in  Milk.  Heim  :  Milch  Zeitung, 
21,  1892. 

6.  Vitality  of  Tuberculosis  Bacilli.  Forster  and  Mann  :  Milch 
Zeitung.  22,  1894. 

7.  Tuberculosis  and  Public  Health,  etc.,  Ivaw.  New  York  Ex- 
periment Station,  Bulletin  No.  65. 

8.  Typhoid  Fever  Disseminated  Through  the  Milk  Supply. 
Russell :  Science,  November  15,  1895. 

9.  Diseases  Conveyed  by  Milk.  B.  Lee  :  Agriculture  of  Penn- 
sylvania, 1894. 

10.  MilkasaSourceof  an  Epidemic  of  Typhoid  Fever.  Schmidt: 
Milch  Zeitung,  23,  1894. 

11.  Danger  from  Consuming  the  Milk  of  Sick  Cows.  F.  Baum  : 
Archiv  wissech  und  praktische  Thierheilkunde,  18,  Heft  384. 

12.  On  Ptomaines  in  Milk.  V.  Malenchini :  Zeitschrift Nahr- 
ungsmittel  Untersuchen  und  Hygine. 

13.  The  Care  of  Milk  for  Cheese  Factories  and  Creameries. 
Ontario  Agricultural  College,  Bulletin  No.  44. 

14.  Cleanliness  in  Handling  Milk.  North  Dakota  Experiment 
Station,  Bulletin  No.  21. 

15.  Milk  of  the  Cow  in  Health  and  Disease.  Blyth  :  Journal 
of  the  Chemical  Society,  1879. 

16.  Poisonous  Milk  and  Milk  Panics.  Wanklyn :  Milk  Anal- 
ysis. 

17.  Milk  Inspection  Affecting  Death  Rate  of  Children.  Milch 
Zeitung,  9.  24  and  349. 


REFKRKNCKS  TO   CHAPTER   X. 


99 


i8.  Milk  of  Other  Domestic  Animals.     Blyth  : 

19.  Diseases  Caused  by  Unwholesome  Milk. 
Pennsylvania,  1894. 

20.  On  Diseased  Milk.     Hiesch :  Analyst;  1878. 


Foods. 
Agriculture  of 


CHAPTER  XI. 
Preserving  Milk. 

The  various  methods  employed  to  presence  milk  all 
follow  one  or  more  of  these  main  lines  : 

1.  Application  of  cold. 

2.  Application  of  heat. 

3.  Use  of  chemicals. 

4.  Condensing. 

79.  Use  of  High  and  Low  Temperatures. — When  fresh 
milk  or  cream  is  cooled  to  50°  F.  or  lower,  it  will  remain 
sweet  for  a  longer  time  than  when  kept  at  a  higher  tem- 
perature. Fermentation  cannot  readily  take  place  at  a 
low  temperature. 

When  the  milk  is  heated  to  200°  to  212° 
F.  for  twenty  minutes,  and  then  sealed 
at  this  temperature,  it  has  undergone 
the  process  known  as  sterilizing.  When 
milk  is  properly  sterilized  and  then  placed 
in  a  cool  room,  it  will  keep  a  long 
time.  A  cheap  and  serviceable  form 
of  sterilizer  is  shown  in  Fig.  20.  When 
the  temperature  registers  higher  than 
159"  or  161°  F.,  the  albumin  coagulates 
and  forms  a  coat  on  the  surface,  com- 
monly known  as  the  "scum."  The  ob- 
ject of  the  sterilizing  is  to  destroy  all  or- 
ganisms in  the  milk.  The  milk  is  sealed  at  the  temper- 
ature at  which  it  is  sterilized  so  as  to  protect  it  from  the 


Fig.  20. 


PASTEURIZING.  lOI 

air  and  to  keep  out  new  colonies  of  organisms.  All  of 
the  organisms  in  sterilized  milk  may  be  destroyed,  but 
the  products  which  these  organisms  have  produced  are 
still  in  the  milk.  Sterilizing  milk  may,  for  example, 
kill  the  tyrotoxicon  organisms,  but  it  does  not  remove 
the  tyrotoxicon  products  ;  again,  sterilizing  the  milk 
from  tuberculous  cows  may  kill  the  tuberculous  organ- 
isms, but  it  cannot  destroy  the  ptomaines  produced  by 
them.  Sterilizing  milk  greatl}^  improves  its  sanitary 
condition. 

Sterilized  unwholesome  milk  cannot,  however,  be 
placed  on  an  equal  footing  with  unsterilized  wholesome 
milk. 

The  preparation  of  sterilized  milk  is  becoming  quite  a 
profitable  and  prominent  feature  of  dairying.  Many 
dairy  farms  have  means  of  sterilizing  the  fresh  milk  and 
putting  it  in  sealed  quart  and  pint  cans.  The  milk  is 
then  sold  at  a  higher  price  to  hospitals  and  for  the  use  of 
children  and  invalids. 

80.  Pasteurizing. — The  pasteurizing  of  milk  is  ac- 
complished at  a  lower  temperature  ;  the  process  being 
to  heat  the  milk  for  a  longer  time,  at  a  lower  temperature, 
157°  to  160°  F.,  so  as  not  to  coagulate  the  albumin 
but  at  the  same  time  to  destroy  the  vitality  of  the  organ- 
isms which  may  be  present  in  the  milk.  In  order  to 
pasteurize  milk  for  family  use,  clean  pint  or  quart  fruit 
cans,  or  bottles  are  first  heated  gradually  in  the  oven  so 
as  to  free  them  from  organisms.  A  pail  or  pan,  pro- 
vided with  a  false  bottom,  is  filled  with  cold  water  so 
that  the  water  will  come  up  to  the  neck  of  the  cans  when 


I02 


THE    CHEMISTRY   OF    DAIRYIXG. 


they  are  set  in  the  water.  Fresh  milk  is  then  put  into 
the  glass  cans  or  bottles,  so  as  to  completely  fill  them. 
The  cans  are  then  placed  into  the  water,  and  the  whole 
is  placed  on  the  stove  and  slowly  heated  until  the  tem- 
I  perature  of  the  w^ater  is  i6o°. 
The  covers  are  then  put^on  the 
cans,  or  the  stoppers  in  the  bot- 
tles. Cork  stoppers  should  never 
be  used.  The  pail  is  removed  to 
the  back  of  the  stove  and  the 
lid  put  on.  After  twenty  min- 
utes the  bottles  are  removed, 
cooled  as  rapidly  as  possible,  and 
then  placed  on  ice.  The  cooling 
restores  the  flavor  to  a  great  ex- 
does  not  have  the  cooked   taste 


M 


Fig.  21. 

tent,  so  that  the  milk 

which  is  so  objectionable  to  many. 

In  the  pasteurizing  of  milk,  use  is  made  of  the  applica- 
tion of  both  heat  and  cold.  Simpl}'  heating  the  milk  to 
1 60°  and  then  allowing  it  to  cool,  unprotected  from  the 
air,  does  but  little  good,  and  may  do  much  harm,  be- 
cause the  milk  in  cooling  down,  cools  slowl}',  and  it  is 
then  in  a  condition  to  be  readily  *  *  re-seeded  ' '  and  to 
allow  rapid  development  of  fresh  organisms  from  the  air 
and  of  those  that  have  escaped  the  pasteurizing  process. 

For  the  pasteurizing  of  milk  on  a  large  scale  there  are 
many  forms  of  apparatus  in  use,  a  description  of  which 
is  not  within  the  province  of  this  work. 

81.  Use  of  Chemicals. — Various  chemical  substances 
are  advertised    to    preserve    milk,    cream,   and    butter. 


CONDENSED   MILK.  IO3 

These  preservatives  are  composed  invariably  of  either 
borax,  boric  acid,  saltpeter,  or  salicylic  acid.  Med- 
ical authorities  seriously  object  to  the  use  of  pre- 
servatives in  milk  or  in  other  foods.  These  chemi- 
cals, when  used  in  excess,  interfere  with  the  process  of 
digestion  and  cause  diarrhoea.  Inasmuch  as  preserva- 
tives are  used  most  liberally  in  summer  and  warm 
weather,  at  the  time  when  bowel  disorders  are  most  prev- 
alent, their  extensive  use  might  be  the  source  of  much 
trouble.  These  chemicals  are  used  to  destroy  the  bac- 
teria in  milk  and  they  are  equally  capable  of  destroying 
those  organisms,  in  the  stomach,  which  carry  on  the  work 
of  digestion.  Inasmuch  as  many  objections  are  urged 
against  their  use,  it  is  safer  not  to  employ  them  and  to 
preserve  milk  by  means  of  some  other  method  which  is 
free  from  objections. 

82.  Condensed  flilk. — Preserving  milk  by  condensing 
it,  is  one  of  the  best  methods  when  the  milk  is  to  be 
kept  for  a  long  time.  When  any  material  is  deprived  of 
its  water,  fermentation  cannot  readily  take  place.  Con- 
densed milk  is  made  by  removing  half  or  more  of  the 
water.  Various  methods  are  employed  for  condensing 
milk,  as  boiling  in  vacuum  pans  under  diminished  pres- 
sure, or  allowing  the  milk  to  flow  over  heated  metallic 
aprons. 


I04  THE    CHEMISTRY    OF    DAIRYING. 

Composition  OF  Condensed  Milk.' 

Condensed  Diluted  three 

milk.  parts   water. 

Per  cent.  Per  cent. 

Water 5040  87.60 

Fat 14-00  3.50 

Milk  sugar 18.00  4-50 

Casein 12.80  3.20 

Albumin 2.00  0.50 

Ash 2.80  0.70 

One  gallon  of  milk  has  been  condensed  to  one  quart, 
hence  when  the  milk  is  used  it  is  to  be  diluted  with  three 
quarts  of  water,  when  it  will  have  the  composition  of  the 
original  milk  and  as  given  in  the  table.  Condensed 
milk  is  extensively  used  in  sea  voyages.  It  is  much  to 
be  preferred  to  poor  milk. 

Of  the  various  methods  employed  to  preserve  milk, 
those  which  make  use  of  high  and  low  temperatures,  as~ 
sterilizing  and  pasteurizing,  are  the  best  and  most  eco- 
nomical ;  condensing  is  more  satisfactory  when  the  milk 
is  to  be  kept  for  a  long  time.  Chemicals  should  not  be 
used  for  preserving  milk. 


REFERENCES  TO  CHAPTER  XI. 

1.  The  Pasteurization  and  Sterilization  of  Milk.  Year  Book 
of  the  United  States  Department  of  Agriculture,  1894. 

2.  Sterilized  Milk.  Duclaux :  Annals  Institute  of  Pasteur,  9, 
1895. 

3.  Pasteurization  of  Milk  and  Cream  for  Direct  Consumption. 
Russell :  Wisconsin  Agricultural  Experiment  Station,  Bulletin 
No.  44. 

4.  A  Preliminary  Bulletin  on  the  Pasteurization  of  Milk. 
Smith  :  Michigan  Experiment  Station,  Bulletin  No.  134. 

1  Analysis  by  author 


REFERENCES   TO   CHAPTER    XI.  105 

5.  The  Action  of  Heat  on  Milk.  Richmond  :  Analyst,  June 
1893- 

6.  The  Sterilization  of  Milk  on  a  Large  Scale.  Hesse  :  Zeit- 
schrift  fiir  Hygiene,  1890,  85. 

7.  The  Chemical  and  Physical  Changes  Attendant  upon  the 
Sterilization  of  Milk.  Leeds  :  Journal  of  the  American  Chem- 
ical Society,  13,  No.  i. 

8.  Methods  of  Milk  Preservation.     Weigmann. 

9.  The  Pasteurization  of  Skim-milk.  Lunde  :  Abstract  in  Ex- 
periment Station  Record,  4,  383. 

10.  Methods  of  Sterilizing  and  Pasteurizing  Milk.  Review  of 
Kinds  of  Apparatus  Used.  Allen  :  Article  in  Recent  Work  on 
Dairying.     Experiment  Station  Record,  5,  1051. 

11.  Pasteurization  and  Milk  Preservation,  with  a  Chapter  on 
Selling  Milk.     Monrad. 

12.  Preservation  of  Milk.     Blyth  :  Foods. 

13.  Experiments  in  Preserving  Milk  Samples.  Newmann : 
Milch  Zeitung,  22,  93. 

14.  Preservatives  and  Their  Importance  in  Dairying.  Kruger  : 
Molkerei  Zeitung,  1892,  No.  34. 

15.  The  Composition  of,  and  Objections  to  the  Use  of,  Preser- 
vatives  in  Milk.     Current  numbers  of  the  Analyst,  1890-91,  etc. 

16.  Compilation  of  Analyses  of  Condensed  Milks.  Konig  : 
Chemie  der  Menschlichen  und  Genussmittel,  Band  II. 


'^^ 


CHAPTER  XII. 

The  Composition  of  Skim-Milk,  Buttermilk  and 

VS^hey. 

Skim-milk,  buttermilk  and  whey  are  quite  frequently 
spoken  of  as  the  by-products  of  milk.  They  are  all  val- 
uable for  feeding  purposes. 

83.  Skim-riilk. — When  the  cream  is  separated  from 
milk,  the  chief  ingredient  which  has  been  removed  is 
the  fat.  The  800  pounds  or  so  of  skim-milk  obtained 
from  1000  pounds  of  milk  contain  nearly  all  of  the 
casein,  albumin  and  ash,  as  well  as  the  milk  sugar 
originally  present  in  the  milk.  The  skim-milk  is,  pound 
for  pound,  more  concentrated  in  these  food  constituents 
than  the  original  milk.  A  hundred  pounds  of  skim- 
milk  is  produced  from  118  or  120  pounds  of  whole  milk 
and  contain  nearly  all  of  the  casein,  albumin  and  milk 
sugar  formerly  present  in  the  118  or  120  pounds  of  milk. 

84.  The  Composition  of  Skim-Milk. — The  most  im- 
portant constituents  of  skim-milk  are  the  casein  and  al- 
bumin, wilich  are  so  essential  for  the  production  of 
muscle  and  a  solid  frame-work  in  young  and  growing 
animals.  The  milk  sugar  is  a  valuable  heat-  and  energy- 
producing  nutrient. 

In  100  pounds  of  skim-milk  there  are  about  three  and 
five-tenths  pounds  of  casein  and  albumin.  When  we 
take  into  consideration  the  small  per  cent,  of  dry  matter 
in  both  whole  milk  and  skim-milk,  this  is  a  relatively 
large  amount  of  muscle-forming  material.     After  remov- 


VALUE   OF    SWKET   AND   SOUR   MILK   PRODUCTS.    107 

ing  the  water  from  100  pounds  of  skim-milk,  there  will 
be  left  about  9.75  pounds  of  solid  matter,  of  which  three 
and  five-tenths  pounds  are  casein  and  albumin,  5.25 
pounds  are  milk  sugar,  a  little  over  0.75  pound  is  ash, 
while  the  remainder  consists  of  fat  and  traces  of  other 
constitents. 

85.  Skim=Milk  and  Whey  Make  Other  Foods  flore 
Valuable. — In  assigning  a  feeding  value  to  skim-milk, 
it  must  be  remembered  that  when  it  is  properly  used, 
skim-milk,  as  well  as  whey,  is  very  valuable  also  in 
making  other  foods  more  palatable  and  digestible. 

Neither  skim-milk,  buttermilk,  nor  whey  are,  when 
fed  alone,  complete  or  balanced  foods  ;  they  are  the  most 
valuable  when  combined  with  grains  or  milled  products, 
as  shorts,  bran,  corn,  oil  meal,  etc.  When  properly 
combined,  the  weak  points  in  the  food  value  and  diges- 
tibility of  the  grains  are  reinforced  by  the  strong  points 
of  the  skim-milk,  while  the  weak  points  of  the  skim- 
milk  are  strengthened  by  the  strong  points  of  the  grains. 

86.  Comparative  Value  of  Sweet  and  Sour  flilk 
Products. — When  souring  takes  place,  some  of  the  milk 
sugar  is  converted  into  lactic  acid.  It  is  very  question- 
able whether  the  acid  which  is  formed  is  as  valuble  for 
food  as  the  original  milk  sugar.  The  ferments,  which 
cause  the  souring  of  the  milk,  may  be  associated  with 
other  ferments  which  produce  products  that  cause  seri- 
ous bowel  troubles. 

Experiments  have  shown  that  for  young  pigs  500 
pounds  of  whey  are  worth  as  much  for  feeding  as  100 
pounds  of   mixed  corn    and    shorts,  which  at  twenty- 


I08  THE    CHEMISTRY    OF    DAIRYING. 

eight  cents  per  bushel  for  the  corn  would  make  the  whey 
worth  ten  cents  per  hundred  pounds. 

When  skim-milk  is  only  about  half  soured,  it  fre- 
quently causes  more  trouble  than  when  it  is  fully  soured, 
and  in  the  curdled  state.  When  fully  soured  the  acid 
may  kill  off  some  of  the  bad  ferments.  The  skim-milk 
should,  when  possible,  be  fed  sweet;  when  partially 
soured  it  is  frequently  very  troublesome.  The  old  skim- 
milk  or  whey,  which  is  left  over  in  the  barrel  from  one 
day,  should  never  be  carried  over  to  another  day,  because 
a  little  old  sour  skim-milk  will  act  as  a  starter  and  will 
soon  sour  and  spoil  a  fresh  lot  of  skim-milk  or  whey 
when  put  into  the  barrel.  In  fact  the  scouring  of  calves, 
when  fed  on  stale  skim-milk,  is  caused  by  ferments 
which  are  present  only  in  the  milk  after  it  has  been  con- 
taminated by  ferments  such  as  the  tyrotoxicon  organism 
which  feeds  upon  stale  and  decomposing  milk  and  other 
foul  matter.  To  prevent  scouring  and  allied  dis- 
eases, the  utmost  cleanliness  and  care  should  be  exer- 
cised in  the  handling  and  feeding  of  skim-milk,  butter- 
milk and  whey,  so  as  to  prevent  the  organisms,  which 
cause  the  bowel  troubles,  from  gaining  access. 

Occasionally  skim-milk  is  over- fed  ;  this  causes  a  great 
deal  of  trouble.  The  chief  benefit  from  the  feeding  of 
skim-milk  comes  from  using  it  moderately. 

When  skim-milk  has  a  little  boiled  or  scalded  ground 
flax-seed  added  to  it  the  mixture  has  nearly  the  same 
composition  as  sow's  milk.  Flax-seed  contains  protein 
and  fat,  the  two  ingredients  which  are  present  in  sow's 
milk  in  liberal  amounts. 


COMPOSITION    OF   WHEY.  lOQ 

When  buttermilk  has  not  been  over-diluted  with  wash 
water  from  the  churn,  it  has  about  the  same  composition 
and  feeding  value  as  skim-milk. 

Sour  whey,  skim-milk,  or  buttermilk  will  act  upon 
tin,  zinc  and  iron,  dissolving  some  of  the  metal.  This 
is  due  to  the  action  of  lactic  acid.  The  tin,  zinc,  and 
iron  compounds  are  all  poisonous  when  taken  in  suffi- 
ciently large  doses.  Hence  it  is  not  advisable  to  store 
sour  whey  or  milk  in  zinc,  tin  or  iron  for  any  great 
length  of  time.  When  spilled  on  iron,  as  the  springs 
and  bolts  of  wagons,  whey  weakens  the  iron  and  in  time 
causes  it  to  become  brittle  and  easily  broken. 

When  whe3"  and  skim-milk  are  spilled  on  floors  and 
near  beams,  they  will  cause  more  rapid  rotting  than  if 
water  were  spilled,  because  the  casein  and  albumin  will 
ferment  and  start  fermentation  and  rotting  of  the  wood. 
The  whey  barrel  should  never  be  placed  near  a  large 
beam  or  directly  over  a  sill. 

87.  Separator  Skim=MiIk.  —  Skim-milks  differ  in 
composition  mainly  in  the  amount  of  fat  present.  Skim- 
milk  from  the  separator  differs  in  no  material  way  from 
ordinary  skim-milk,  except  in  the  more  thorough  re- 
moval of  the  fat,  by  the  gravity  process.  Separator 
skim-milk  sours  very  readily,  because  in  cooling  down 
from  the  temperature  of  separation  it  remains  at  70°  to 
90°  F.  for  a  number  of  hours,  which,  with  a  little  old 
skim-milk  in  the  vat  as  a  starter,  are  the  most  favorable 
conditions  for  souring. 

88.  Composition  of  Whey. — One  hundred  pounds  of 
whey  contain  about  seven  pounds  of  dry  matter,  of  which 


no  THE    CHEMISTRY   OF   DAIRYING. 

five  pounds  are  milk  sugar.  Whey  contains  from  eight- 
tenths  to  one  per  cent  of  protein,  mainly  in  the  form  of 
albumin.  The  albumin  in  the  milk  is  not  recovered  in 
cheese-making,  but  finds  its  way  into  the  whey.  It  is 
the  albumin  in  the  whey  which  gives  it  its  chief  feeding 
value.  There  is  not  as  much  ash  in  w^hey  as  in  milk  or 
skim-milk,  because  a  part  of  the  ash  is  combined  with 
the  casein  and  is  recovered  in  the  cheese.  In  addition 
to  the  milk  sugar  and  albumin,  whey  also  contains  about 
0.65  per  cent,  ash  and  a  small  variable  amount  of  fat. 
The  most  essential  difference  in  composition  between 
skim-milk  and  whey  is  the  casein  which  is  present  in 
the  skim-milk,  but  not  in  the  whe5^ 

The  composition  of  each  of  the  by-products  of  milk  is 
given  in  the  following  table : 

Composition  of  One  Hundred  Pounds  of 

Cow's  Skim-  Butter 

milk.  milk.  milk.  Whey. 

Water,  lbs 87.50  90.25  90.50  93.00 

Fat 3.50  0.20  0.20  0.35 

Casein  and  albumin.  3.25  3.60  3.30  0.80 

Sugar 5.00  5.15  5.30  5.20 

Ash 0.75  0.80  0.70  0.65 


REFERENCES  TO  CHAPTER  XII. 

1.  Analyses  of  Skim-milks.  Massachusetts  State  Experiment 
Station,  Annual  Reports  for  1888,  1889,  1890,  1891,  1892,  1893, 
1894,  1895,  1896. 

2.  The  Composition  of  Skim-milk.  Maine  Experiment  Station, 
Annual  Report  for  1890. 

3.  The  Composition  of  Skim-milk.  New  York  State  Experi- 
ment Station,  Annual  Report  for  1890. 


REFKRKNCES   TO   CHAPTER   XII.  Ill 

4.  Analyses  of  Skim-milks.  Wisconsin  Experiment  Station, 
Annual  Report  for  1889. 

5.  The  Composition  of  Whey.  New  York  State  Experiment 
Station,  Bulletins  Nos,  37,  43,  45,  46,  47. 

6.  The  Composition  of  Buttermilk.  Maine  Experiment  Sta- 
tion, Annual  Report  for  1890. 

7.  The  Composition  of  Skim-milk  and  Whey.  C.  B.  Cochran  : 
Journal  of  the  American  Chemical  Society,  i5>  No.  6. 

8.  The  Feeding  Value  of  Skim-milk.  Massachusetts  State  Ex- 
periment Station,  Annual  Reports  for  1884,  1885, 1886,  1887,  1888, 
1889,  etc. 

9.  The  Effects  of  Skim-milk  in  a  Ration  for  Pigs.  Maine  Ex- 
periment Station,  Annual  Report  for  1889. 

10.  The  Feeding  Value  of  Skim-milk.  Vermont  Experiment 
Station,  Bulletin  No.  18. 

11.  The  Effects  of  Skim-milk  in  a  Ration  for  Pigs.  New  Hamp- 
shire Experiment  Station,  Bulletin  No.  11. 

12.  The  Comparative  Feeding  Value  of  Skim-milk  and  Butter- 
milk.    Wisconsin  Experiment  Station,  Annual  Report  for  1886. 

13.  The  Comparative  Feeding  Value  of  Buttermilk  and  Skim- 
milk.  Massachusetts  State  Experiment  Station,  Annual  Reports 
for  1884,  1885. 

14.  The  Comparative  Value  of  Sweet  and  Sour  Skim-milk. 
Vermont  Experiment  Station,  Annual  Report  for  1891. 

15.  The  Feeding  Value  of  Whey.  Wisconsin  Experiment  Sta- 
tion, Bulletin  No.  27. 

16.  The  Average  Composition  of  Skim-milk,  Buttermilk  and 
Whey,  Konig  :  Chemie  der  Menschlichen  und  Genussmittel, 
Band  II. 


CHAPTER  XIII. 
Other  Methods  Employed  in  Milk  Testing,   and  the 

Adulteration  of  Dairy  Products. 
[~;89.  other   Methods    Employed    in    niIk=Testing.— 

There  are  a  number  of  other  simple  methods  which  are 
occasionally  emplo^-ed  for  testing  milk.  Many  of  these 
methods  are  reliable,  but  they  require  more  skill  and 
time  than  the  Babcock  test,  and  hence  the}^  are  not  so 
generall}'  used. 

90.  Beimling  Method. — This  test  is  quite  similar  to  the 
Babcock  test ;  a  centrifugal  is  used.  The  test-bottles 
are  smaller,  and  two  acids  instead  of  one  are  made  use 
of.  Wood  alcohol  is  required  ;  this  is  quite  apt  to  be 
impure  and  cause  too  high  results.  With  the  Beimling 
method  care  must  be  taken  to  obtain  pure  wood  alcohol. 

9i.  The  Lactochrite  is  a  method  which  has  been  in  use 
in  Germany  and  Denmark  for  some  time.  The  separa- 
tion of  the  fat  is  made  by  means  of  acetic  and  sulphuric 
acids,  combined  with  centrifugal  action.  In  its  w^ork- 
ings  it  is  quite  like  the  Babcock  test.  The  centrifugal 
used  is  in  form  like  the  "Alpha"  separator.  The  method 
is  patented  and  the  apparatus  expensive.  The  method 
gives  reliable  results. 

92.  Gerber's  Butyrometer. — In  this  method  the  fat  is 
separated  by  centrifugal  action,  aided  by  sulphuric  acid 
and  wood  alcohol.  This  method  is  a  combination  of  the 
more  important  features  of  the  Babcock  and  the  Beimling 
methods.  It  gives  accurate  results  and  is  quite  exten- 
sively used  in  Europe. 

93.  Short's  riethod. — In  this  test  an  alkali  solution  is 
first  added  to  the  milk,  which  changes  the  fat  into  soap. 


LACTOSCOPE   AND    FKRSER'S    PIOSCOPE.  II3 

The  soap  is  then  converted  into  insoluble  fatty  acids  by 
adding  sulphuric  acid.  The  fatty  acids  are  then  meas- 
ured in  a  graduated  tube.  In  this  method  test-bottles, 
similar  to  those  used  in  the  Babcock  test,  are  employed. 
The  test-bottles  frequently  break  and  muchmore  time  is 
required  than  for  the  Babcock  test. 

94.  Cochrane's  Method.— The  fat  is  separated  by  a 
mixture  of  sulphuric  and  acetic  acids  and  ether  is  then 
used  to  raise  the  fat  into  a  graduated  tube,  where  it 
is  measured.  The  Cochrane  fat  bottles  are  made  with 
two  tubes,  one  for  measuring  the  fat  and  the  other  for 
adding  the  reagents. 

All  of  the  above  methods  are  patented,  while  the  Bab- 
cock method  is  not. 

95.  In  Failyer  and  Willard's  Method  an  acid  is  first 
added  to  the  milk,  and  then  gasoline  to  collect  the  fat. 
The  gasoline  is  removed  by  a  current  of  air.  The  fat  is 
then  brought  up  into  a  graduated  neck  and  measured. 

96.  The  Lactoscopeand  Ferser's  Pioscope  were  methods 
once  in  use.  They  are  optical  methods  and  depend  upon 
the  opacity  of  the  milk  serum.  They  are  totally  unreli- 
able and  the  results  are  very  inaccurate.  Neither  method 
should  ever  be  used.  None  of  these  short  methods  are 
sufficiently  accurate  for  scientific  work,  or  as  final  evi- 
dence in  court  in  case  of  adulteration,  except  in  the 
hands  of  skilled  operators. 

In  the  chemical  laboratory,  the  chemist  makes  use  of 
what  is  known  as  the  gravimetric  method,  where  the  fat 
in  the  milk  is  carefully  separated  and  weighed  on  a  deli- 
cate balance. 


114  '^^^    CHEMISTRY    OF    DAIRYING. 

ADULTERATION  OF  DAIRY  PRODUCTS. 

97.  Butter. — x\rtificial  butter  is  found  on  the  market 
in  the  well-known  forms  of  oleomargarin  and  butterin. 
These  products  are  made  mainly  from  beef  drippings. 
The  fats  are  first  put  through  filter  presses,  remove 
a  portion  of  the  harder  fats,  which  are  used  for 
candles  and  soap-making.  The  softer  fats  which  pass 
through  the  press  are  introduced  into  large  churns,  to- 
gether with  sweet  milk,  and  then  churned,  salted,  and 
colored  so  as  to  resemble  butter.  In  trade  there  is  a 
slight  difference  betw^een  oleomargarin  and  butterin  ; 
oleomargarin  is  the  harder  and  has  the  higher  melting- 
point.  Oleomargarin  is  used  to  suppl}'  Southern  trade, 
while  butterin  is  sold  in  Northern  markets. 

The  distinguishing  difference  between  butter  and 
these  products  is  the  presence  or  absence  of  the  charac- 
teristic fat,  butyrin  found  in  butter,  to^  the  extent  of 
nearly  seven  per  cent. 

98.  Cheese  is  adulterated  (i)  by  removing  the  fat 
from  the  milk  and  making  skim-milk  cheese  ;  (2)  b}^ 
removing  the  fats  from  the  milk  and  substituting  other  and 
cheaper  fats,  thus  producing  what  is  called  filled  cheese. 
Filled  cheese  is  made  by  first  passing  the  milk  through 
a  separator  to  remove  the  fat,  and  then,  while  the  milk 
is  still  in  the  vat  and  warm,  addingl  ard  or  cottolene  to 
the  milk  and  thoroughly  mixing  it  before  the  rennet  is 
added. 

99.  A  Simple  flethod  for  Testing  the  Purity  of  But- 
ter-Fats.— Take  a  piece  of  butter  or  material  about  the 
size  of  a  peanut,  put  it  in  a  glass  or  porcelain  dish,  add 


TESTING   THE   PURITY   OF   BUTTKR-FATS. 


115 


a  little  water,  and  a  piece  of  potash  about  the  size  of  the 
fat.  Place  the  dish  in  warm  water  for  an  hour  or  so  on 
the  back  of  a  stove  until  it  makes  soap.  When  cool  care- 
fully add  about  10  cc.  sulphuric  acid  to  liberate  the 
butyric  acid,  which  is  like  the  concentrated  odor  of  stale 
butter.  Genuine  butter  will  give  an  intense  odor  of 
butyric  acid,  which  cannot  be  mistaken.  Oleomargarin 
will  give  scarcely  any  reaction  for  butyric  acid. 

In  order  to  detect  the  presence  of  foreign  fats  in 
cheese,  the  chemist  first  extracts  the  fat  from  the  cheese 
and  then  determines  the  amount  of  butyric  acid  present. 
If  the  skimming  has  been  done  very  thoroughly  and 
foreign  fats  added,  the  foreign  fats  can  be  detected  by 
first  sampling  the  cheese  in  the  same  way  as  in  testing 
for  the  per  cent,  of  fat  in  cheese  by  the  Babcock  test. 

The  pieces  of  cheese  are  put  into  a  small  bottle,  gaso- 
line is  added,  one-half  teacupful  is  sufficient,  the  bottle 
corked  and  thoroughly  shaken.  The  bottle  is  then 
allowed  to  stand  for  a  few  minutes,  and  the  gasoline, 
which  has  dissolved  the  fat,  is  poured  off  into  a  teacup. 
The  dish  is  placed  in  the  open  air  and  the  gasoline  evapo- 
rated, leaving  the  fat  deposited  in  the  cup.  Do  not 
let  the  gasoline  evaporate  in  a  room  where  there  is  a  fire 
or  a  light.  The  fat  is  then  tested  for  butyric  acid  in  the 
same  way  as  the  butter-fat.  If  the  skimming  has  been 
only  partially  done  the  test  will  not  show  decisive 
results. 

The  injury  which  results  from  the  sale  of  oleomarga- 
rin and  filled  cheese  is  due  to  its  being  a  dishonest 
competitor  more  than  to  its  unwholesomeness.     People 


Il6  THE    CHEMISTRY   OF   DAIRYING. 

buy  these  materials,  intending  to  purchase  pure  butter 
or  cheese.  As  to  the  digestibility  of  oleomargarin, 
there  have  been  but  few  experiments  made,  and  these 
few  experiments  have  shown  it  to  be  less  digestible  than 
butter,  so  that  the  claim  that  it  is  equally  as  digestible  as 
butter  is  simpl}-  a  statement  that  is  not  based  on  any 
number  of  exact  experiments. 

When  the  butter  or  cheese  is  submitted  to  chemical 
analj^sis,  the  fat  is  first  separated,  and  then  the  amount 
of  butyric  acid  products  determined.  Five  grams  of  pure 
butter-fat  will  require  from  twenty-three  to  twenty-six 
cc.  of  a  tenth  normal  alkali  solution  to  neutralize  the 
volatile  butyric  acid  products. 


REFERENCES  TO  CHAPTER  XIII. 

1.  A  New  Milk  Test  (Beimling's).  Vermont  Experiment  Sta- 
tion, Bulletin  No.  24. 

2.  Determining  the  Fat  in  Milk.  Leffmann  and  Beam  :  Ana- 
lyst, 18,  193. 

3.  Acid  Butj-rometer.     Gerber  :  Chemiker  Zeitung,  16,  839. 

4.  The  Lactocrite.     Blyth :  Analyst,  12,  34. 

5.  The  Lactocrite.  United  States  Department  of  Agriculture, 
Division  of  Chemistry,  Bulletin  No.  13. 

6.  The  Lactocrite.     Biedermann's  Centralblatt,  17,  627. 

7.  A  New  Method  for  Detecting  the  Fat  in  Milk.  Short :  Wis- 
consin Experiment  Station,  Bulletin  No.  16. 

8.  The  Determining  of  Fat  in  Milk  by  Short's  Method.  Jour- 
nal of  Analytical  Chemistry,  2,  Part  4. 

9.  Cochran's  Method  for  Determining  the  Fat  in  Milk.  Jour- 
nal of  Analytical  Chemistry,  3,  Part  4. 

10.  A  Description  of  Cochran's  Method  for  Determining  the 
Fat  in  Milk.  Cornell  University  Experiment  Station,  Bulletin 
No.  17. 


RKFKRKNCES   TO   CHAPTER   XIII.  II 7 

11.  Simple  Methods  of  Determining  Milk  Fat  (Short's  and 
Cochran's).     Pennsylvania  Experiment  Station,  Bulletin  No.  12. 

12.  Failyer  and  Willard's  Method  for  Determining  the  Fat  in 
Milk.     Journal  of  Analytical  Chemistry,  3,  Part  3. 

13.  Parson's  Method  for  Determining  the  Fat  in  Milk.  Jour- 
nal of  Analytical  Chemistry,  3,  Part  3. 

14.  The  Oil  Test  for  Cream.  Wisconsin  Experiment  Station, 
Bulletin  No.  12. 

15.  Patrick's  Method  of  Testing  Milk.  Iowa  Experiment  Sta- 
tion, Bulletins  Nos.  8  and  11. 

16.  Milk  Tests,  Comparison  of  Simple  Methods.  Illinois  Ex- 
periment Station,  Bulletins  Nos.  10  and  14. 

17.  Comparison  of  Various  Methods  for  Testing  Milk.  West 
Virginia  Experiment  Station,  Third  Annual  Report. 

18.  Milk  Tests.  Handbook  of  Experiment  Station  Work, 
United  States  Department  of  Agriculture. 

19.  Feser's  Lactoscope.     Versuchs-Stationen,  27,  2,  135. 

20.  The  Lactoscope.     Biedermann's  Centralblatt,  9,  302. 

21.  Methods  of  Manufacturing  Butter  Substitutes;  Whole- 
someness  of  Artificial  Butter  ;  The  Adulteration  of  Butter,  In- 
cluding References  and  Methods  of  Analysis.  Wiley  :  United 
States  Department  of  Agriculture,  Division  of  Chemistry : 
Foods  and  Food  Adulterants,  Part  First,  Dairy  Products. 

22.  Extent  and  Character  of  Food  Adulterations.  Wedder- 
burn  :  United  States  Department  of  Agriculture,  Division  of 
Chemistry,  Bulletins  Nos.  25  and  32. 

23.  The  Analysis  and  Adulteration  of  Foods.  Part  III.  James 
Bell. 

24.  The  Adulteration  of  Butter  and  Cheese.  Blyth  :  Foods, 
Their  Composition  and  Analysis. 

25.  La  Margarine  et  les  semili  beurres.     Cluseret. 

26.  Der  Kampf  gegen  die  Margarine.     Heinrich  Frankel. 
Reports  on    the  Nature   and  Extent    of   the    Adulteration  of 

Dairy  Products  : 

27.  State  Dairy  and  Food  Commission  of  Minnesota,  St. 
Paul. 


ii8 


THE    CHEMISTRY    OF    DAIRYING. 


28.  State  Board  of  Health  of  Pennsylvania.     Philadelphia. 

29.  State  Dairy  Commission  of  New  Jersey.     Trenton. 

30.  State  Board  of  Health  of  Massachusetts,     Boston. 

31.  State  Dairy  Commission  of  Iowa.     Des  Moines. 

32.  State  Dairy  and  Food  Commission  of  Ohio.     Columbus. 

33.  State  Dairy  Commission  of  New  York.     Albany. 

34.  State  Dairy  and  Food  Commission  of  Wisconsin.     Madi- 
son. 


^••< 


CHAPTER  XIV. 

Effect  of  Food   upon   the  Quality  of  Dairy 
Products. 

The  nature  and  quality  of  the  food  consumed  has, 
in  many  cases,  a  marked  effect  upon  the  quality  as  well 
as  upon  the  quantity  of  milk  produced  by  different  cows. 
The  quality  of  the  milk  is  capable  of  being  influenced  to 
a  greater  extent  than  is  the  proximate  composition  ; 
that  is,  the  quality  of  the  milk  fats,  as  hard  or  soft,  can 
be  influenced  more  than  the  per  cent,  of  fat. 

The  fat  which  is  present  in  the  milk  is  not  produced 
entirely  from  the  fat  in  the  food.  Neither  does  the  fat 
in  the  food  find  its  way,  directly  and  unchanged,  into 
the  milk.  The  fats,  as  well  as  the  other  food  compounds 
first  undergo  digestion.  They  are  then  reconstructed 
within  the  body  before  passing  into  the  milk.  The  fat 
in  the  milk  may  be  produced  from  either  the  fats,  non- 
nitrogenous  compounds,  or  proteids  of  the  food.  Al- 
though the  fat  and  other  compounds  -of  the  food  do  not 
pass  directly  into  the  milk,  but  first  undergo  reconstruc- 
tion within  the  body,  nevertheless  the  nature  of  the  fat, 
etc.,  produced  in  the  milk  is  greatly  influenced  by  the 
nature  of  the  building  materials,  originally  present  in 
the  food. 

loo.  Production  of  Hard  Butters.— Cotton-seed  meal, 
the  product  obtained  by  removing  the  oil  from  cotton 
seed,  when  fed  in  large  amounts  produces  a  butter  with 
a  very  high  melting-point,  in  some  cases  io°  higher  than 


I20  THE    CHEMISTRY    OF    DAIRYING. 

ordinary  butter.  Chemical  analj'sis  shows  that  such  a 
butter  is  rich  in  stearin  and  palmitin.  The  fats  in 
the  cotton-seed  meal  have  not  been  taken  directh'  into 
the  milk.  The  fat  and  protein  of  the  cotton-seed  meal  have 
been  first  broken  down  in  the  digestive  tract  and  then 
the  large  amounts  of  digested  hard  fat  products 
have  influenced  the  production  of  stearin  and  palmitin 
in  the  milk.  In  case  cotton-seed  meal  is  fed,  the  milk, 
when  put  through  the  separator,  must  be  warmed  5°  to 
10°  higher  than  ordinar}^  milk,  otherwise  the  separator 
will  clog.  In  fact,  the  milk  must  be  handled  in  a  differ- 
ent way  throughout,  because  of  the  higher  melting-point 
of  the  fat. 

loi.  Production  of  Soft  Butter. — Linseed  oil,  the 
product  obtained  by  removing  the  oil  from  flaxseed, 
when  fed  in  large  amounts,  has  a  tendency  to  produce  a 
soft  butter.  The  fat  and  protein  of  the  linseed  meal 
have,  in  a  general  way,  the  opposite  effect,  from  the 
cotton-seed  meal,  upon  the  quality  of  the  fat  in  the 
milk.  As  in  the  case  of  the  cotton-seed  meal,  the  fat 
and  protein  of  the  food  do  not  pass  directly  into  the 
milk,  but  simply  the  digested  products  of  the  linseed 
meal  favor  the  production  of  a  softer  butter. 

102.  Effects  of  Balanced  Rations  upon  the  Quality  of 
the  Milk  Fat. — The  feeding  of  balanced  rations  has  a 
marked  effect  upon  the  quality  of  the  butter  produced. 
The  main  object  of  feeding  a  balanced  ration  is  to  fur- 
nish the  body  with  just  the  right  amount  and  kind  of 
food,  so  that  there  will  be  enough  protein  and  other 
nutrients  for  the  support  of  the  body  and  the  production 


ENSILAGE  AND  ITS  EFFECTS  UPON  THE  MILK.       121 

of  milk.  An  unbalanced  ration  produces  an  abnormal 
butter,  as  the  following  example  will  show  :  When  cows 
are  fed  only  hay  and  potatoes,  the  quantity  of  milk  pro- 
duced is  greatly  lessened,  while  the  butter  is  very  much 
like  tallow.  The  hay  and  potatoes  are  deficient  in  pro- 
tein. When  grain  is  fed  along  with  the  hay  and  pota- 
toes, making  a  balanced  ration,  the  butter  is  of  unusually 
good  quality. 

103.  Peculiarities  of  Different  Foods  upon  the  Nature 
of  the  flilk  Fats. — As  a  general  rule  the  coarse  fodders, 
as  hay,  corn  stalks,  and  straw,  which  are  deficient  in 
protein,  have  a  tendency  to  produce  hard  and  tallow-like 
butter. 

Corn  meal,  when  fed  in  large  amounts,  has  a  tendency 
to  produce  a  mediumly  firm  butter.  Gluten  meal,  a  prod- 
uct of  corn,  produces  a  softer  butter  than  corn  meal. 

Oats,  when  fed  in  large  amounts,  produce  a  firm  but- 
ter of  good  quality,  but  which  is  sometimes  a  little 
crumbly.  When  oats  and  corn  are  fed  together,  as  is 
usually  the  case,  the  butter  is  of  very  good  quality  be- 
cause the  tendency  of  the  oats  to  produce  a  crumbly  butter 
is  neutralized  by  the  opposite  tendency  of  the  corn. 
Bran  and  shorts  both  produce  good  normal  butter  of 
neither  to6  hard  nor  of  too  soft  a  quality. 

104.  Ensilage  and  Its  Effects  upon  the  flilk. — The 
effect  of  ensilage  upon  the  quality  of  milk  has  been  quite 
extensively  studied .  When  fed  with  coarse  fodders  it  has 
a  tendency  to  produce  a  softer  butter,  improving  the 
quality,  because  the  ensilage  is  fed,  when  the  coarse  fod- 
ders have  the  tendency  to   produce  over-hard   butter. 


122  THE    CHEMISTRY   OF    DAIRYING. 

The  ensilage  odor  imparted  to  the  milk  is  due  more  to 
the  odors  gaining  access  to  the  milk  through  the  air 
during  and  after  milking.  It  frequently  happens  that 
the  stables,  through  imperfect  ventilation,  are  thoroughly 
saturated  with  the  ensilage  products.  As  soon  as  the 
milk  is  drawn  it  becomes  saturated.  When  cows  which 
are  fed  on  ensilage  are  milked  in  a  place  free  from  the 
ensilage  odors,  there  is  scarcely  a  trace  of  the  ensilage 
taste  in  the  milk. 

105.  Effects  of  some  Green  Fodders  and  Weeds  upon 
the  Quality  of  Hilk.  —  Some  green  fodders  have  a 
marked  effect  upon  the  taste  of  milk.  Rye  fodder,  for 
example,  if  fed  when  it  begins  to  head  out,  produces  a 
fish-like  taste  in  the  milk.  This  is  due  to  the  fodder 
at  that  state  containing  compounds  like  trimethylamine 
which  produce  the  peculiar  taste  in  milk.  Rye  fodder, 
however,  is  a  valuable  fodder  if  cut  and  cured  at  the 
right  time  ;  it  does  not  then  produce  this  taste  in  the 
milk. 

Many  weeds  are  also  responsible  for  bad-tasting  milk. 
Wild  mustard  contains  two  bitter  principles  which  im- 
part flavor.  Wild  garlic  also  produces  a  foul-tasting 
milk.  The  volatile  sulphur  oil  present  in  turnips,  as  is 
well-known,  passes  directly  into  the  milk.  All  members 
of  the  rape  family,  containing  the  volatile  oil  of  rape, 
impart  a  characteristic  taste  to  milk. 

106.  The  Desirable  Flavors  of  Butter  and  Cheese.— 
The  flavor  produced  in  good  butter  and  cheese  is  supposed 
to  be  due  largely  to  the  working  of  bacteria.  The  bac- 
teria produce  definite   chemical   compounds,   and  it  is 


REFERENCES   TO   CHAPTER    XIV.  123 

these  compounds  which  impart  the  flavor  to  butter  and 
cheese— both  the  desirable  and  the  undesirable  ones. 
It  is  now  the  aim  of  the  bacteriologist  and  the  chemist  to 
study  the  products  produced  by  each  class  of  organisms, 
and  the  conditions  which  are  favorable  or  unfavorable 
for  their  development,  so  as  to  control  the  workings  of 
the  desirable  ones,  and  prevent  the  action  of  the  unde- 
sirable ones. 


REFERENCES  TO  CHAPTER  XIV. 

1.  The  Composition  of  Butter-fat  as  Affected  by  Food.  New 
Hampshire  Experiment  Station,  Bulletins  Nos.  16  and  18. 

2.  Effect  of  Food  upon  the  Quality  of  Butter.  Article  on  But- 
ter-making in  Handbook  of  Experiment  Station  Work.  United 
States  Department  of  Agriculture. 

3.  Effect  of  Cotton-seed  Meal  on  the  Composition  of  Butter. 
Texas  Experiment  Station,  Bulletins  Nos.  11  and  14. 

4.  Effect  of  Cotton-seed  Meal  on  Butter.  Alabama  (College) 
Experiment  Station,  Bulletin  No.  25. 

5.  Injurious  Effects  of  Certain  Plants  on  Milk  and  its  Products. 
Milch  Zeitung,  1892,  46. 

6.  The  Effect  of  Peanut  Cake  and  Cotton-seed  Cake  on  the  Fat 
Content  of  Milk.     Backaus  :  Journal  fiir  I,andwirtschaft,  41,4. 

7.  Effects  of  Different  Kinds  of  Food  upon  Butter.  A.  Mayer  : 
Die  Landwirtschaftlichen  Versuchs-Stationen,  41. 

8.  Influence  of  Food  upon  the  Qualities  of  Butter-fat.  Frear  : 
Agricultural  Science,  1893,  7. 

9.  Transmission  of  Nitrates  to  Milk.  Richmond  :  Analyst, 
1893,  279. 

10.  On  the  Effect  of  Feeding  Fat  to  Cows.  Wing:  Cornell 
University  Experiment  Station,  Bulletin  No.  92. 

11.  Recovery  of  the  Food  Ingredients  in  the  Milk.  New  York 
State  Experiment  Station  Report,  1891. 


124  THE    CHEMISTRY   OF    DAIRYING. 

12.  Effects  of  Rye  Pasture  on  the  Taste  of  Milk.  Breeder's 
Gazette,  26,  203,  220,  239. 

13.  Transmission  of  Substances  from  Food  to  Milk.  Frohner : 
Zeitschrift  fiir  Fleisch-  und  Milcli  Hygiene,  10,  i. 

14.  Influence  of  the  Quality  of  Food  upon  the  Economy  of  Milk 
and  Butter  Production.  Pennsylvania  Experiment  Station,  An- 
nual Report  for  1895. 

15.  Quality  of  Butter  as  Affected  by  Food.  Pennsylvania  Ex- 
periment Station,  Bulletin  No.  17. 

16.  Influence  of  Roots  and  Silage  on  the  Composition  of  Milk. 
Pennsylvania  Experiment  Station  Report,  1890. 

17.  The  Quality  of  Butter  as  Effected  by  Food.  Maine  Exper- 
iment Report,  1891. 

18.  Effects  of  Feed  upon  the  Quality  of  Milk.  Iowa  Experi- 
ment Station,  Bulletins  Nos.  13,  14,  16,  17. 


CHAPTER  XV. 

The  Composition  of  Fodders  and  the  Calculation 
of  Rations. 

107.  Importance. — Before  a  cow  can  produce  milk  she 
must  be  supplied  with  food  ( i )  for  the  production  of 
heat,  and  (2)  for  furnishing  materials  to  renew  the  worn- 
out  tissues  of  her  body.  After  the  body  has  been  sup- 
plied with  food  for  these  two  purposes,  whatever  food  is 
left  over  is  used  for  either  producing  milk  or  flesh.  With 
a  dairy  cow  this  surplus  food  goes  for  the  production  of 
milk.  There  is  a  great  difference  in  the  way  in  which 
cows  make  use  of  their  food.  Some  cows  require  a 
smaller  amount  of  food  for  supplying  the  needs  of  their 
bodies  than  others.  A  cow  that  requires  a  large  amount 
of  food  for  the  support  of  her  body  and  produces  a  small 
return  in  milk  yield  is  an  unprofitable  cow. 

Inasmuch  as  the  milk  is  produced  from  the  food  which 
is  in  excess  of  that  required  for  the  support  of  the  body, 
it  naturally  follows  that  the  production  of  milk  depends 
very  largely  upon  the  kind  and  quantity  of  food  con- 
sumed. Some  combinations  of  food  are  favorable  for 
milk  production,  while  other  combinations  are  very  un- 
favorable. The  combining  of  foods  so  as  to  supply  the 
right  amount  and  kind  of  food  is  spoken  of  as  *  *  rational 
feeding."  The  feeding  of  farm  animals  and  dairy 
stock,  is  in  itself  a  separate  subject  of  study.  In  this 
work  only  the  brief  outline  of  the  subject  of  the  rational 


126  THE    CHEMISTRY    OF    DAIRYING. 

feeding  of  dairy  stock,  will  be  given.  Our  knowledge 
regarding  the  feeding  of  rations  is  based  upon  the  results 
of  extended  investigations  in  chemistr}^  and  physi- 
ology. 

io8.  Heat=  Producing  and  Tissue=Renewing  Foods. — 
The  foods  which  produce  heat  are  those  which  con- 
tain the  most  fat  and  starch-like  materials.  The  foods 
which  are  the  most  valuable  for  renewing  the  worn-out 
tissues  of  the  bodies  are  those  which  contain  a  group  of 
compounds  known  as  protein.  Clover,  peas,  oats,  oil- 
meal,  bran,  shorts,  and  wheat  all  contain  a  good  supply 
of  protein  and  are  valuable  for  renewing  worn-out  tis- 
sues of  the  body  and  stimulating  milk  production.  Corn 
fodder,  silage,  potatoes,  and  roots,  are  food-stuffs  which 
are  rich  in  starch  or  heat-producing  materials.  Hence  a 
mixing  or  blending  of  these  two  cla.sses  of  foods,  the 
heat-producing  and  the  tissue-renewing  and  milk-stimu- 
lating ones,  produces  the  best  results.  The  combining 
of  these  two  classes  of  foods  forms  what  is  known  as  a 
balanced  ration,  and  the  composition  of  the  foods  is  the 
basis  for  their  combination. 

EXPLANATION  OF  TERflS  USED. 

109.  Water  in  Food=stuffs. — In  all  foods,  even  those 
which  have  been  thoroughly  sun-  and  air-dried,  there  is 
an  appreciable  amount  of  water.  Substances  like  meal 
and  flour,  which  appear  perfectly  dry,  are  not  free  from 
water.  In  the  tables  of  analyses  the  figures  for  water 
represent  the  amount  which  is  present  in  a  hundred 
pounds  of  the  material.  The  last  traces  of  water  are  re- 
moved by  drying  the  substance  in  an  oven  at  a  tempera- 


ORGANIC    COMPOUNDS.  1 27 

ture  of  212°  F.,  when  all  of  the  water  in  the  material  is 
converted  into  steam  and  escapes. 

no.  The  Dry  Substance  is  what  is  left  after  all  of  the 
water  has  been  removed  from  any  material.  Frequently 
the  results  of  analyses  are  given  on  the  basis  of  the  dry 
substance,  or  water-free  material,  as  it  is  called.  In  this 
work  all  of  the  results  are  given  on  the  basis  of  the  orig- 
inal material,  or  the  material  as  it  is  ordinarily  used  as 
food,  unless  otherwise  stated. 

111.  The  Ash.— The  ash  is  what  is  left  after  the  sub- 
stance is  burned.  It  is  sometimes  called  the  mineral  or 
inorganic  part.  The  ash  is  important,  inasmuch  as  it 
furnishes  the  main  portion  of  the  necessary  materials  for 
bone-growth.  Too  much  ash,  especially  when  it  is  rich 
in  silica  (sand),  or  in  strong  alkalies,  is  objectionable. 
The  ashes  of  all  grains  are  usually  the  richest  in  phos- 
phates, and  hence  the  most  valuable  for  bone-growth.  In 
nearly  all  mature  agricultural  plants  there  is  less  than 
ten  per  cent.  ash.  There  is  generally  a  sujB&cient  amount 
of  ash  in  all  food  products  for  bone-growth. 

112.  Organic  Matter.— The  organic  matter  is  that  por- 
tion of  a  fodder  which  is  converted  into  volatile  products 
when  the  dry  matter  is  burned  ;  the  organic  matter  is 
found  by  subtracting  the  ash  from  the  dry  matter. 

113.  The  Non-Nitrogenous  and  Nitrogenous  Organic 
Compounds. — From  the  feeder's  point  of  view  the  or- 
ganic matter  of  food-stuffs  may  be  divided  into  two  large 
classes  of  compounds  :  (i)  The  non-nitrogenous,  and 
(2)  the  nitrogenous  compounds.     The  division  is  made 


128  THE    CHEMISTRY    OF    DAIRYING. 

according  to  the  presence  or  absence  of  the  element, 
nitrogen.  Starch,  sugar,  fat,  and  cellulose  contain  no 
nitrogen,  and  are  non-nitrogenous  compounds.  Albu- 
min, casein,  and  fibrin  contain  nitrogen,  and  hence  are 
nitrogenous  compounds. 

114.  Non=Nitrogenous  Compounds. — The  non-nitrog- 
enous compounds  include  the  fiber  (cellulose  and  lig- 
nin),  starches,  sugars,  fats,  pectose  substances,  organic 
acids,  volatile  or  essential  oils,  and  other  compounds. 
The  non-nitrogenous  compounds  do  not  all  possess  the 
same  food  value.  The  non-nitrogenous  compounds 
make  up  by  far  the  larger  portion  of  the  dry  matter  of  a 
fodder.  There  is  from  four  to  ten  times  more  of  the  non- 
nitrogenous  compounds  in  any  ordinary  food  than  nitrog- 
enous compounds.  There  is  usuall}^  a  sufficient  amount 
of  non-nitrogenous  materials  in  all  foods,  but  the  nitrog- 
enous compounds  are  liable  to  be  too  deficient. 

115.  Ether  Extract. — The  compounds  which  are  solu- 
ble in  ether  are  called  the  ether  extract.  In  the  grains 
and  milled  products  the  ether  extract  is  nearly  pure  fat ; 
in  hay,  grass,  and  other  coarse  fodders  the  ether  extract 
is  from  fifty  to  sevent3'-five  per  cent,  pure  fat.  All  fats 
contain  about  one-half  more  carbon  than  does  starch  or 
sugar ;  hence  when  the  fats  are  digested  and  undergo 
oxidation  within  the  body,  they  produce  over  twice  as 
much  heat  as  starch  or  sugar.  The  fat  in  the  food  has 
much  to  do  with  producing  heat  in  the  body,  and  but 
little  to  do  directly  with  furnishing  fat  for  the  produc- 
tion of  milk.  In  fact,  any  good  cow  will  give  much 
more  fat  in  her  milk  for  a  given  period  than  there  is  fat 


THK    NITROGENOUS   COMPOUNDS.  1 29 

in  her  food.  A  certain  amount  of  fat  in  a  food  is  essen- 
tial ;  too  large  a  quantity,  when  not  associated  with  a 
sufl5.cient  amount  of  protein,  is  objectionable. 

116.  Crude  Fiber. — The  fiber  includes  the  cellulose 
and  lignin,  which  constitute  the  framework  of  the 
plant.  The  fiber  is  not  entirely  indigestible.  An  ordi- 
nary amount  of  fiber,  when  associated  with  sufiicient 
amounts  of  the  right  kinds  of  other  digestible  materials 
is  unobjectionable.  The  fiber  and  ash  of  the  food,  as 
ordinarily  used,  ought  not  to  exceed  forty  to  fifty-five 
per  cent,  of  the  total  nutrients,  because  they  represent 
too  much  inert  material  in  a  fodder. 

117.  Nitrogen=Free  Extract. — The  nitrogen-free  ex- 
tract includes  the  sugars,  starch,  pectose  substances  and 
all  non-nitrogenous  compounds  which  are  soluble  in 
dilute  acid  and  alkali  solutions.  The  term  means  easily 
soluble  bodies,  free  from  nitrogen.  The  nitrogen-free 
extract  includes  all  of  the  non-nitrogenous  compounds 
except  the  fat  and  fiber.  The  term  nitrogen-free  extract 
is  a  very  indefinite  one,  and  is  employed  because  no 
better  classification  has  as  yet  come  into  general  use. 
In  the  potato  the  nitrogen-free  extract  consists  mainly 
of  starch  ;  in  the  sugar  beet  it  consists  of  sugar  ;  in  straw 
it  consists  largely  of  pentosans,  and  in  fruit  it  consists 
mainly  of  pectose  substances. 

1 18.  The  Nitrogenous  Compounds — The  characteristic 
building  material  of  these  compounds  is  the  element  ni- 
trogen. The  nitrogenous  compounds  are  by  far  the 
most  expensive  and  the  most  important  materials  found 


130  THE    CHEMISTRY    OF    DAIRYING. 

in  food-Stuffs.  Unfortunately  the  terms  emplo^-ed  to 
designate  these  bodies  are  somewhat  confused.  By  many 
the  terms  nitrogenous  compounds,  proteids,  and  al- 
buminoids are  used  synonymously  ;  each  term,  how- 
ever, has  a  separate  and  distinct  meaning.  The  total 
nitrogenous  compounds  is  the  term  employed  to  desig- 
nate all  of  the  organic  nitrogenous  compounds  of  a  food- 
stuff. The  term  protein  represents  only  a  single  class  of 
the  nitrogenous  bodies.  All  nitrogenous  compounds 
are  not  proteids,  but  all  proteids  are  nitrogenous  com- 
pounds. The  albuminoids  are  another  distinct  class  of 
the  nitrogenous  compounds,  while  albumins  and  albu- 
minates are  subclasses  of  the  proteids.  In  the  tables  of 
analyses  the  term  crude  protein  is  used.  Crude  protein 
includes  the  protein  and  other  bodies,  as  amines  and 
alkaloids,  which  are  not  proteids.  In  the  grains  and 
milled  products  the  crude  protein  is  ninety-five  percent, 
or  more  true  protein,  while  in  potatoes  and  root  crops 
about  half  of  the  crude  protein  is  true  protein. 

119.  Importance  of  Protein. — For  food  purposes,  pro- 
tein is  the  largest  and  most  important  class  of  the  nitrog- 
enous compounds.  The  proteids  are  the  materials  out 
of  which  the  muscles  are  formed  ;  the  proteids  enter  into 
the  composition  of  the  tissues  of  the  nervous  system,  the 
ligaments,  bones,  hoofs,  hair,  and  all  of  the  vital  fluids. 
The  protein  compounds  are  the  nutrients  which  are  so 
important  for  tissue-renewing  purposes.  A  certain 
amount  of  protein  in  the  food  is  absolutely  necessary, 
and  this  protein  must  be  supplied  before  grow^th  or  the 
production  of  milk  can  take  place. 


HEAT   UNITS.  131 

120.  Digestible  Nutrients. — In  all  fodders  and  grains 
there  is  a  certain  amount  of  each  of  the  food  nutrients 
which  is  indigestible  and  cannot  be  counted  upon  for 
food  purposes.  The  amounts  of  the  various  indigestible 
nutrients  in  fodders  have  been  determined  by  a  number 
of  our  American  experiment  stations.  In  the  tables  of 
analyses  the  composition  of  100  pounds  of  fodder  as  or- 
dinarily used  is  first  given,  and  then,  in  the  same  line, 
under  digestible  nutrients,  the  pounds  of  each  digestible 
nutrient  in  100  pounds  of  the  fodder,  are  given.  The  di- 
gestible nutrients  represent  the  amount  which  can  ordi- 
narily be  counted  upon  for  actual  food  purposes. 

121.  Nutritive  Ratio. — The  term  nutritive  ratio  is  fre- 
quently made  use  of  in  connection  with  rational  feeding. 
The  nutritive  ratio  is  the  ratio  which  exists  between  the 
digestible  protein  and  the  digestible  non-nitrogenous 
compounds.  A  nutritive  ratio  of  i  to  6.7  means  one  part 
of  digestible  protein  to  every  six  and  seven-tenths  parts 
of  digestible  non-nitrogenous  compounds.  A  wide  ration 
means  a  large  amount  of  non-nitrogenous  compounds, 
and  a  narrow  ration  a  comparatively  small  amount. 

122.  Heat  Units. — When  the  food  is  digested  it  pro- 
duces heat,  which  is  transformed  into  muscular  energy. 
The  heat  which  is  produced  can  be  measured  by  the 
work  which  it  is  capable  of  doing.  The  heat  produced 
is  measured  in  calories.  A  calorie  is  the  amount  of  heat 
required  to  raise  a  kilogram  of  water  from  0°  to  i''  in  the 
Centigrade  scale,  or  approximately  2.2  pounds  of  water, 
1.8°  on  the  Fahrenheit  scale.  One  pound  of  digestible 
fat  yields  4225  calories.     One  pound  of  digestible  starch 


132  THE    CHEMISTRY    OF    DAIRYING. 

and  nitrogen-free  extract  compounds  yields  i860  calo- 
ries. One  pound  of  digestible  protein  yields  the  same 
amount  of  heat  as  one  pound  of  starch  ;  viz.,  i860.  The 
amount  of  heat  produced  by  fodders  can  be  calculated 
by  the  use  of  these  factors  : 

One  pound  digestible  fat  produces..-  4225  calories. 
One  pound  digestible   starch,  protein 

and  other  nutrients  produces i860  calories. 

123.  Standard  Ration. — An  ordinarj^  cow  of  1000 
pounds  weight,  should  receive  about  twenty-five  pounds 
of  organic  matter  per  day.  This  organic  matter  should 
contain  from  2.25  to  2.5  pounds  of  digestible  protein 
and  produce  about  30,000  heat  units. 

124.  How  to  Calculate  a  Ration. — In  order  to  calcu- 
late a  ration  it  is  first  necessary  to  consider  the  compo- 
sition of  the  foods  which  are  to  be  used.  In  case  that 
you  are  using  coarse  fodders,  which  are  poor  in  protein, 
it  will  be  necessary  to  use  some  grain  or  milled  product 
which  is  more  concentrated  in  protein.  Suppose  that 
you  have  clover  hay,  corn  fodder,  and  bran,  and  you  de- 
sire to  make  a  ration  containing  these  three  articles  of 
food.  Ten  pounds  of  clover  hay,  and  five  pounds  each 
of  corn  fodder  and  bran  will  contain  in  all  about  1.40 
pounds  of  digestible  protein.  This  is  not  a  sufficient 
amount  of  protein.  Ten  pounds  each  of  clover  hay, 
corn  fodder  and  bran  will  contain  about  2.10  pounds  of 
digestible  protein,  which  is  not  far  from  the  required 
amount,  but  more  protein  could  be  added  with  advan- 
tage to  the  ration,  so  the  clover  hay  is  increased  to 
twelve  pounds.     In  the  table  of  the  average  composition 


HOW   TO   CAI.CULATE    A    RATION.  133 

of  American  feeding  stuffs  the  per  cent,  of  digestible  nu- 
trients is  given  : 

Ether  Non-ni- 

Crude  protein.             extract.  trogenous. 

Per  cent.                  Per  cent.  Per  cent. 

Clover 6.5                       1.6  34-9 

Corn  fodder 1-8                        1.2  32.0 

Bran 12-6                        2.9  44.1 

These  figures  represent  the  amounts  of  digestible  nu- 
trients in  100  pounds  of  food-stuff.  The  amount  in  one 
pound  would  then  be  o.oi  part  of  these  amounts.  The 
digestible  crude  protein  in  twelve  pounds  of  clover  hay 
is  0.065  X  12  =  0.78  pound  ;  ether  extract,  0.016  X  12  = 
0.192  pound  ;  non-nitrogenous,  0.349  X  12=  4.19.  Ten 
pounds  of  corn  fodder  contain  :  Protein,  10  X  0.018  = 
0.18  pound;  ether  extract,  10X0.012  =  0.12  pound; 
non-nitrogenous,  0.32  X  10=  3.2  pounds.  Ten  pounds 
of  bran  contain:  Protein,  0.126  X  10  =  1.26  pounds; 
ether  extract,  0.029X10  =  0.29  pound;  non-nitroge- 
nous compounds,  0.441  X  10  =  4.41  pounds.  Tabulating 
the  results  gives  : 

Dige;stibi,k  Nutrients. 

Fiber  and 
Crude  Ether    nitrogen-free 

protein.         extract.  extract. 

Clover,  12  pounds 0.78  0.19  4.19 

Corn  fodder,  10  pounds. ..     0.18  0.12  3.20 

Bran,  10  pounds 1.26  0.29  4.41 

Total 2.22  0.60  11.80 

Heat  units  :  (11.80 -f  2.22)  X  18.60  =  26077 
4225  X    0.6   =  2535 

Total  =  28612 
Nutritive   ratio:    0.6x2.25=1.35.       ii-8o+i.35_ 

2.22  ^^ 

The  nutritive  ratio  is  i  to  5.9. 


134  I'HE    CHEMISTRY   OF   DAIRYING. 

In  calculating  the  nutritive  ratio,  the  ether  extract  is 
first  multiplied  by  2.25  because  the  fats  are  so  much 
more  concentrated  than  the  other  non- nitrogenous  com- 
pounds. 

This  ration  contains  2.22  pounds  of  digestible  crude 
protein  and  will  produce  about  28,600  heat  units.  This 
is  not  too  far  from  the  standard.  The  ration  could  to 
advantage  have  about  five  pounds  of  roots  of  some  kind 
added  to  it. 

125.  Roots  or  Silage  Desirable  in  a  Ration. — A  good 
ration  should  also  contain  a  small  amount  of  some  suc- 
culent food,  as  silage,  roots,  or  potatoes.  In  feeding 
roots  they  should  be  freed  as  much  as  possible  from  dirt. 
Five  or  ten  pounds  per  day  of  roots  is  as  much  as  should 
be  fed.  These  foods  are  valuable  on  account  of  favora- 
bly effecting  the  digestion  of  the  ration. 

126.  Bulky  and  Concentrated  Rations. — A  ration 
should  not  be  too  bulky,  neither  should  it  be  too  con- 
centrated. The  digestive  organs  are  capable  of  taking 
care  of  from  twenty-five  to  thirty-two  pounds  of  dry 
matter,  and  from  fifty  to  ninety  pounds  of  water  per  day. 
When  bulky  foods  are  fed  in  excess  the  organs  of  diges- 
tion are  overworked.  A  cow,  if  fed  entirely  on  hay,  as 
timothy  or  prairie  hay,  would  have  to  consume  sixty  to 
seventy  pounds  of  hay  in  order  to  obtain  the  2.25  pounds 
of  digestible  protein.  This  is  over  twice  the  digestive 
capacity  of  the  cow.  In  the  same  way  a  food  may  be 
too  concentrated.  A  ration  of  five  pounds  of  bran,  four 
pounds  of  linseed  meal,  and  some  fatty  material  would 
supply  all  of  the  necessary  digestible  protein  and  heat 


COST    OF    FODDERS    AND    GRAIN.  1 35 

units,  but  such  a  mixture  would  be  an  objectionable 
ration  because  it  is  too  concentrated  and  the  digestive 
tract  will  not  have  enough  bulk}'  food. 

127.  Requirements  of  Different  Animals. — In  the 
feeding  of  rations  it  is  to  be  remembered  that  the  varia- 
tions in  the  requirements  of  different  animals  must  be 
considered.  A  ration  which  is  well  suited  for  a  small 
cow  may  have  to  be  increased  for  a  larger  cow.  If  a 
cow  consumes  all  of  her  ration,  and  then  appears  anxious 
for  more,  she  should  not  necessarily  be  restricted  to  the 
ration.  The  standard  ration  is  to  be  considered  as  a 
guide  rather  than  an  inflexible  rule.  Ordinarily,  a 
daily  ration  of  ten  pounds  of  mixed  grain,  twenty  pounds 
of  hay  and  coarse  fodder,  together  with  a  few  roots,  will 
make  a  good,  balanced  ration. 

Many  of  our  most  successful  dairymen,  who  lay  no 
claim  or  stress  upon  the  rational  feeding  of  their  stock, 
have  learned  from  experience  how  to  combine  the  food 
in  just  about  the  right  way  to  form  a  balanced  ration. 

128.  Comparative  Cost  and  Composition  of  Fodders 
and  Grain. — The  dairyman  should  consider  the  relative 
cost  of  fodders  and  grains,  as  well  as  their  composition. 
The  market  value  of  dairy  fodders  is  frequently  quite 
different  from  the  actual  food  values  of  those  fodders. 
In  order  to  compare,  in  a  general  way,  the  cost  and  food 
value  of  fodder  articles,  first  calculate  the  number  of 
pounds  of  fodder  or  grain  that  can  be  purchased  for  one 
dollar  ;  for  example,  which  is  the  cheaper  food,  corn  at 
20  cents  per  bushel  or  oats  at  12  cents  per  bushel  ?  A 
dollar  will  buy  280  pounds  of  corn  and  265.6  pounds  of 


136  THE    CHEMISTRY    OF    DAIRYING. 

oats.  In  the  280  pounds  of  corn  there  are  25.8  pounds 
of  digestible  protein  and  440,335  heat  units.  In  the 
265.6  pounds  of  oats  there  are  24.5  pounds  of  protein 
and  342,626  heat  units.  The  amount  of  protein  in  these 
two  foods  is  nearly  the  same,  but  the  dollar's  worth  of 
corn  will  procure  over  100,000  more  heat  units  than  the 
dollar's  worth  of  oats.  In  order  to  calculate  the  amount 
of  digestible  protein  and  heat  units  that  can  be  obtained 
for  one  dollar,  multiply  the  number  of  pounds  of  the 
material  purchased  for  one  dollar  by  the  per  cent,  of 
digestible  matter,  as  given  in  the  tables. 

In  purchasing  fodders  the  preference  should  first  be 
given  to  the  protein.  When  there  is  but  a  slight  differ- 
ence in  the  amount  of  digestible  protein  in  two  foods, 
purchase  the  one  containing  the  larger  number  of  heat 
units.  In  some  cases  a  dollar's  worth  of  mixed  food 
will  furnish  more  nutrients  or  a  better  balanced  ration 
than  if  just  one  of  the  foods  were  purchased.  In  order  to 
compare  the  food  value  of  grains  and  fodders  at  different 
prices,  a  table  has  been  prepared  (see  Appendix,  p.  144) 
which  gives  the  number  of  digestible  pounds  of  the  sepa- 
rate nutrients  and  the  heat  units  in  a  dollar's  worth  of 
the  material,  when  the  prices  are  as  stated  in  the  table. 
When  the  prices  are  different  from  those  given  in  the 
table,  the  amount  of  each  nutrient  which  may  be  procured 
for  one  dollar  can  be  calculated  from  the  composition  of 
the  material  in  the  way  explained. 


REFERENCES  TO  CHAPTER  XV. 
[Note.— The  literature  on  this  subject  is  so  extensive  that  only 
a  few  typical  references  are  given.     For  references   to  special 


REFERENCES   TO   CHAPTER    XV.  137 

topics,  as  the  characteristic  value  of  any  food  for  milk  produc- 
tion, the  student  is  referred  to  the  card  catalogue  index  issued 
by  the  United  States  Department  of  Agriculture,  Office  of  Exper- 
iment Stations.  In  calculating  rations,  it  is  best  to  use  the  fig- 
ures given  for  the  average  composition  of  American  feeding 
stuffs,  except  in  those  cases  where  extended  special  investiga- 
tions have  been  made  of  the  fodders  of  a  State  by  an  Experi- 
ment Station.] 

1.  Manual  of  Cattle  Feeding.     Armsby. 

2.  Landwirtschaftliche  Fiitterungslehre.     Emil  Wolff. 

3.  Feeding  Farm  Animals.  Allen  :  Office  of  Experiment  Sta- 
tions, United  States  Department  of  Agriculture,  Farmer's  Bul- 
letin No.  22. 

4.  A  Compilation  of  Analyses  of  American  Feeding  Stuffs. 
Jenkins  and  Winton :  Office  of  Experiment  Stations,  United 
States  Department  of  Agriculture,  Bulletin  No.  38. 

5.  One  hundred  American  Rations  for  Dairy  Cows.  Woll : 
Wisconsin  Experiment  Station,  Bulletin  No.  38. 


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TABI.E  Giving  the  Number  of  Pounds  of  Digestible  Nutri- 
ents AND  Heat  Units  that  Can  be  Obtained   for  One 
Dollar   When  Grains  and  Milled  Products  are 
AT  Different  Prices. 

Dig-estible  pounds  of 

Dry      Pro-  Carbohy-    Heat 

Price,  matter.  teid.s.  Fat.    drates.  units. 

Corn,  per  bushel |  0.20     224     25.8  8.7     191. 8  440335 

Corn,  per  bushel 0.25     179     20.6  6.9     153.4  352854 

Barley,  per  bushel 0.35       97     12.5  2.5       80.9  184123 

Oats,  per  bushel 0.12     175     24.5  10.4     136.0  342626 

Oats,  per  bushel 0.15     140     19.6  8.3     108.8  274032 

Oats,  per  bushel 0.18     116     16.4  6.9      90.7  226949 

Oil  meal,  per  ton 14.00     102     39.4  10.4      47.9  206416 

Oil  meal,  per  ton 15.00       95     36.8  9.7       44.7  192634 

Oil  meal,  per  ton 16.00      89     34.5  9.1       41.9  180611 

Cotton-seed  meal,  per  ton.   14.00       93     45.0  14.0       29.0  199173 

Cotton-seed  meal,  per  ton.   16.00      81     40.0  12.5       25.2  174084 

Rye,  per  bushel 0.45      88     13.0  2.0      72.0  166550 

Timothy  hay,  per  ton 8.00     127      9.0  3.0     108.0  230295 

Prairie  hay,  per  ton 6.00     163     11. o  4.0     138.0  294040 

Clover  hay,  per  ton 10.00     105     15.0  3.0      82.0  193095 

Millet  hay,  per  ton 8.00     138     lo.o  3.0     121. o  256236 

Wheat  shorts,  per  ton 10.00     134     20.0  4.6     11 1.8  264583 

Wheat  shorts,  per  ton 8.00     168     25.0  5.8     140.0  330728 

Wheat  shorts,  per  ton 6.00     223     33.3  7.7     186.3  440673 

Wheat  bran,  per  ton jo.oo     120     25.0  7.2       84.2  333532 

Wheat  bran,  per  ton 8.00     150    31.3  9.0     105.3  291910 

Wheat  bran,  per  ton 6.00     200    41.7  12.0     140.3  389220 

Potatoes,  per  bushel 0.15       95       8.4  ...       79.2  162936 


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APPENDIX. 


Review  Questions  for  Classroom  Use. 

I.  What  are  the  milk  solids,  and  how  are  they  obtained? 
2,  State  the  average  composition  of  milk  ;  which  constituent  is 
the  most  variable  ?  3.  What  is  the  size,  form,  and  appearance 
of  the  fat  globules?  4.  Why  do  they  retain  this  shape?  5. 
How  does  the  size  of  the  globules  vary  with  the  period  of  lacta- 
tion and  individuality  of  the  cow  ?  6.  What  is  the  milk  serum 
and  what  can  be  said  about  its  constancy  of  composition  ?  7. 
Why  is  it  necessary  to  take  into  consideration  the  quantity  of 
milk  as  well  as  its  composition  in  calculating  the  amount  of 
fat  produced  ?  8.  How  can  the  total  pounds  of  each  constituent 
of  the  milk,  given  by  a  cow  in  one  day,  be  determined,  when  the 
composition  is  known  ?  9.  What  is  the  difference  in  composition 
between  the  first  milk  and  the  strippings  ?  10.  What  is  gained 
by  testing  milk  ?  11.  How  is  the  ash  in  milk  determined  ?  12. 
How  does  milk  vary  in  composition  ?  13.  What  is  the  differ- 
ence between  butter  and  milk  fats?  14.  What  is  the  albumin  in 
milk?  15.  Define  solids  not  fat.  16.  How  should  a  sample  of 
milk  be  taken  ?  17.  How  is  the  milk  measured  with  the 
pipette?  18.  Describe  the  various  pieces  of  apparatus  used  in 
testing  milk  with  the  Babcock  test.  19.  Explain  the  best 
method  employed  to  read  the  fat.  20.  How  can  the  machine  be 
speeded?  21.  How  is  the  acid  to  be  handled  and  what  is  to  be 
avoided  ?  22.  What  is  the  result  when  the  acid  is  either  too 
strong  or  too  dilute?  23.  How  can  the  test-bottles  be  tested? 
24.  What  are  the  agents  which  cause  the  milk  fats  to  separate  in 
the  Babcock  milk  test?  Explain  the  question  in  detail.  25. 
Name  the  four  separate  fats  of  which  milk  fat  is  composed.  26. 
What  can  you  say  about  the  reliability  of  the  Babcock  test?  27. 
How  about  its  use  for  testing  skim-milk  ?  28.  Which  of  the 
milk  fats  impart  the  hard  qualities  to  butter  ?  Which  one  the 
soft  quality?  29.  Which  fat  is  characteristic  of  butter,  and  how 
does  butter  differ  in  composition  from  oleomargarine,  etc.?  30. 
What  compound  is  common  to  all  fats  ?  31.  What  is  saponifica- 
tion? 32.  What  is  the  difference  in  composition  between  butter 
and  oleomargarin,  etc.?  33.  How  doe?  milk  sugar  differ  from 
common  sugar?  34,  What  is  produced  out  of  milk  sugar  when 
milk  sours?  35.  How  is  it  produced  ?  36.  What  are  the  condi- 
tions favorable  for  its  production?  37.  How  is  the  acid  in  milk 
determined?     38.  Why  is  not  all  of  the  milk  sugar  made  into 


148  APPENDIX. 

lactic  acid  ?  39.  Explain  the  working  of  the  starter.  40.  Why 
is  care  necessary  in  the  selection  of  a  starter  ?  41.  What  is  the 
object  of  the  alkali  test  for  lactic  acid?  42.  Explain  the  work- 
ing of  the  lactometer.  43.  To  what  extent  is  it  reliable?  44. 
Explain  how  it  can  be  used  jointly  with  the  Babcock  test  to  tell 
the  character  of  the  milk  45.  What  effect  has  the  temperature 
upon  the  working  of  the  lactometer?  46.  How  can  the  test  and 
lactometer  be  used  in  determining  the  solids  in  milk?  47.  Be 
prepared  to  give  opinions  of  milk,  as  fat  2.80,  sp.  gr.  1.026, 
watered  or  skimmed.  48.  Draw  the  three  positions  of  the  lac- 
tometer :  skim-milk,  watered  milk,  whole  milk.  49.  What  can 
3'ou  say  regarding  the  composition  of  cream  ?  50.  How  does  the 
composition  of  skim-milk  vary  according  to  the  methods  of 
creaming  employed?  51.  How  is  the  amount  of  fat  in  cream 
determined?  52-  With  separator  work,  what  per  cent,  of  fat 
ought  to  be  returned  in  the  butter?  53.  What  changes  occur  to 
the  fat  globules  while  churning?  54.  Why  is  it  necessary  to 
churn  different  creams  at  different  temperatures?  55.  How 
does  the  ripeness  of  the  cream  effect  the  churning  ?  56.  State 
the  necessary  conditions  for  creaming  milk  by  the  cold,  deep- 
setting  process.  57.  How  does  the  amount  of  total  fat  lost  in 
the  skim-milk  compare  with  the  amount  lost  in  the  buttermilk? 
58.  How  does  a  can  of  milk  set  in  water  at  60-^  compare  as  to 
rapidity  and  thoroughness  of  creaming  with  a  can  set  in  water 
at  44^  ?  59.  How  does  the  amount  of  water  and  foreign  matter 
effect  the  keeping  qualities  of  butter?  60.  State  the  average 
composition  of  butter.  61.  Show  how  a  difference  in  the  tem- 
perature of  the  washing,  working  and  churning  of  butter  effects 
the  per  cent,  of  water  retained  in  the  butter.  62.  State  briefly 
what  becomes  of  the  various  constituents  in  milk  when  butter  is 
made.  63.  What  are  the  nitrogenous  compounds  of  milk  ?  64. 
How  does  casein  and  albumin  differ  in  regard  to  the  action  of 
heat?  65.  What  is  rennet,  and  what  two  principles  does  it  irn- 
part  to  the  milk?  66.  Explain  the  hot  iron  test  and  what  it  is 
used  for.  67.  Explain  the  rennet  test  and  what  it  is  used  for. 
68.  Explain  the  action  of  the  "starter."  69.  How  much  of  the 
solid  matter  of  the  milk  is  recovered  in  the  cheese  ?  70.  State 
briefly  where  the  constituents  in  the  milk  go  in  the  process  of 
of  cheese-making.  71.  State  how  the  amount  of  milk  required 
to  make  a  pound  of  cheese  varies  with  the  composition  of  the 
milk.  72.  How  can  skim-milk  cheese  be  told  from  whole  milk 
cheese?  73.  Explain  the  comparative  losses  of  fat  when  cheese 
is  made  from  milk  poor  in  fat,  and  from  milk  rich  in  fat.  74. 
Give  the  composition  of  cheese.  75.  What  conditions  determine 
the  amount  of  water  in  cheese  ?     76.  What  causes  the  changes 


APPENDIX.  149  , 

in  the  curd  while  in  the  vat?  What  is  this  change  similar  to  ? 
77.  How  would  you  determine  the  amount  of  fat  in  cheese?  78. 
Give  the  conditions  in  cheese-making  for  the  production  of  a 
quick-curing  and  early-market  cheese.  79.  Give  the  conditions 
for  making  a  long-keeping  cheese.  80.  What  is  the  ripening  of 
cheese?  81.  What  are  the  two  most  important  conditions  for 
ripening  cheese?  82.  How  is  the  amount  of  moisture  in  the 
curing  room  determined?  83.  Explain  the  construction  and 
workings  of  the  hygrometer.  84.  What  can  you  say  about  the 
justice  for  the  paying  for  milk  in  cheese  factories  by  the  Bab- 
cock  test?  85.  How  does  the  amount  of  cheese  produced  from 
a  pound  of  fat  compare  with  different  milks  ?  86.  How  could 
you  compare  the  gross  proceeds  for  butter-making  and  cheese- 
making  on  the  basis  of  the  test?  Be  prepared  to  work  an  exam- 
ple. Don't  learn  the  figures;  they  will  be  given  you.  87.  How 
are  the  dividends  for  either  a  cheese  factory  or  a  creamery  to  be 
made  out  on  the  basis  of  the  test  ?  Be  prepared  to  work  an  ex- 
ample. 88.  How  can  you  determine  the  amount  of  butter  that 
can  be  made  from  a  certain  amount  of  butter  fat  on  the  basis  of 
your  own  work?  89.  What  is  the  composite  sample  and  how  is 
it  made  use  of?  90.  What  may  be  used  for  preserving  the  milk 
in  the  composite  samples?  91.  How  can  the  test  be  made  when 
the  number  of  cows  in  the  herd  is  small  ?  92.  How  are  the 
skim-milk  test-bottles  different  in  structure  from  the  ordinary 
test-bottles?  93.  What  is  the  ash  of  milk?  94.  What  is  the 
value  of  ash  as  a  food?  95.  What  is  the  lime  in  the  milk  com- 
bined with  ?  96.  What  two  compounds  are  found  in  milk  ash  in  the 
largest  amounts?  97.  What  is  colostrum  milk?  98.  Why  is  it 
called  colostrum?  99.  What  effect  has  colostrum  upon  the 
value  of  butter  or  cheese?  100.  What  is  tyrotoxicon?  loi. 
How  does  the- tyrotoxicon  get  into  milk?  102.  What  is  urea  and 
what  does  an  abnormal  amount  of  it  in  milk  signify  ?  103. 
What  is  the  (yellow)  color  of  milk  due  to?  104.  What  relation 
does  this  color  bear  to  the  fat  content  ?  105.  What  are  the  but- 
ter colors  composed  of  ?  106.  Why  is  not  the  use  of  butter 
colors  adulterating  butter?  107.  What  is  lacto-fibrin  ?  108. 
What  effect  has  it,  as  far  as  known,  upon  the  creaming  of  milk? 
109.  What  are  the  best  proofs  of  the  presence  of  fibrin  in  milk? 
no.  What  effect  has  partial  freezing  upon  the  composition  of 
the  unfrozen  milk?  in.  What  is  the  nature  of  the  gases  in 
fresh  pure  milk?  112.  When  milk  gets  old,  how  does  the  nature 
of  the  dissolved  gases  change?  113.  Give  the  tests  for  a  good 
dairy  salt.  114.  How  may  an  impure  salt  effect  the  taste  of  but- 
ter? 115.  To  what  extent  is  milk  subject  to  change  in  chemical 
composition  during  transportation?     116.  What  results   haV^e 


I50 


APPENDIX. 


been  obtained  on  this  question?  117.  What  is  the  aeration  of 
milk?  118.  When  and  how  should  milk  be  aerated?  119. 
What  effect  has  aeration  upon  the  quality  of  cheese  produced? 
120.  How  would  you  determine  when  it  is  advisable  to  mix  the 
milk  of  fresh  cows  with  the  milk  of  cows  well  along  in  their 
milking  period?  121.  What  is  the  result  of  mixing  under  such 
conditions  when  the  milk  is  creamed  by  gravity  process?  122. 
What  effects  has  delay  and  cooling  upon  the  gravity  creaming 
process?  123.  Why  is  a  delay  not  advisable?  124.  When  milk 
is  creamed  by  gravity  processes  it  is  advisable  to  add  very  much 
hot  or  cold  water  to  the  milk?  125.  Give  three  reasons  why 
this  is  not  advisable.  126.  What  effects  have  different  diseases 
upon  the  chemical  composition  of  milk?  127.  With  only 
such  appliances  as  found  at  home,  how  would  you  distinguish 
an  unwholesome  milk  from  one  that  would  probably  be  all 
right?  128.  What  four  factors  mainly  influence  the  sanitary 
condition  of  milk?  129.  How  and  why  may  milk  be  the  cause 
of  the  spreading  of  contagious  diseases  ?  130.  State  the  main 
difference  in  composition  between  mare's  milk  and  cow's  milk. 
131.  Between  cow's  milk  and  sow's  milk.  132.  Between  cow's 
milk  and  the  milk  from  sheep  and  goats.  133.  Name  the  four 
methods  employed  for  preserving  milk.  134.  Explain  the  dif- 
ference between  sterilizing  and  pasteurizing  of  milk.  135. 
What  effect  has  the  cooling  in  the  pasteurizing  process  ?  136. 
Why  is  the  use  of  chemicals  objectionable  for  preserving  milk  ? 
137.  State  how  you  would  pasteurize  milk  for  family  use  on  the 
small  scale.  138.  Why  is  milk  sterilized  or  pasteurized?  139. 
Why  is  pasteurized  poor  milk  not  as  good  as  unpasteurized  good 
milk?  140.  What  is  condensed  milk  and  how  is  it  made?  141. 
How  about  the  feeding  value  of  both  sweet  and  sour  whey  ? 

142.  How  does  skim-milk    differ   in   composition    from   whey? 

143.  How  does  separator  skim-milk  differ  from  deep-setting  skim- 
milk?  144.  What  can  you  say  about  the  composition  of  butter- 
milk? 145.  Why  is  it  objectionable  to  store  old  whey  in  iron, 
tin,  or  zinc  vats?  146.  Why  should  the  old  whey  or  skim-milk 
never  be  carried  over  to  the  next  day  in  hot  weather?  147. 
What  additional  feeding  value  does  whey,  skim-milk  and  butter- 
milk possess  in  addition  to  the  nutrients  which  they  contain  ?  148. 
Why  not  locate  the  whey  barrel  over  a  large  beam  or  sill  ?  149. 
Why  is  it  that  skim-milk,  whey  or  buttermilk  alone  are  not 
complete  foods  ?  150.  Why  is  it  preferable  to  feed  skim-milk 
fully  soured  rather  than  partially  soured?  151.  Why  does  sepa- 
rator skim-milk,  as  usually  handled,  sour  so  quickly  ?  152. 
What  can  you  say  regarding  the  working  of  the  lactocrite  and 
the  reliability  of  the  results?    153.     In  what  respects  is  the 


APPENDIX.  151 

Babcock  method  superior  to  other  methods,  as  Short's,  Coch- 
raue's,  etc.  ?  154.  What  can  you  say  regarding  the  lactoscope, 
and  the  pioscope  ?  155.  What  is  the  gravimetric  method  for  fat 
determination?  156.  How  is  butter  adulterated  ?  157.  In  what 
ways  may  cheese  be  adulterated  ?  158.  How  would  you  detect 
a  sample  of  oleomargarin?  159.  How  could  you  detect  a  sam- 
ple of  filled  cheese  when  the  skimming  has  been  done  by  a  sepa- 
rator? 160.  Why  is  this  test  not  reliable  when  the  milk  has 
been  only  partially  skimmed  ?  161.  What  is  the  main  objection 
to  the  use  of  oleomargarin,  etc.?  162.  State  the  average 
amount  of  dry  matter,  digestible  protein,  and  heat  units  which 
an  ordinary  dairy  ration  should  contain?  163.  What  is  the 
function  of  the  protein  of  the  food  ?  164.  Of  the  fats  and  carbo- 
hydrates ?  165.  What  is  a  balanced  ration?  166.  How  would 
you  proceed  to  calculate  a  ration  ?  Be  prepared  to  work  an  ex- 
ample. 167.  Why  is  a  bulky  ration  objectionable?  168.  Why  is 
a  ration,  of  very  small  bulk,  yet  containing  all  the  nutrients, 
objectionable?  169.  What  is  gained  by  feeding  a  balanced 
ration?  170.  Does  the  nature  of  the  food  influence  the  percent- 
age composition  of  milk  or  does  it  influence  the  quality  more? 
171.  What  is  the  fat  in  milk  prodcued  from?  172.  Explain  the 
effects  upon  the  quality  of  the  butter,  of  the  following  foods 
when  fed  in  large  amounts  :  Cottonseed  meal,  linseed  meal,  corn 
meal,  gluten  meal,  ground  oats,  coarse  rough  fodders,  ensilage, 
bran,  shorts.  173.  What  is  the  effect  of  an  unbalanced  ration, 
as  hay  and  potatoes,  upon  the  quality  of  butter?  174.  Effect  of 
a  balanced  ration  ?  175.  The  odor  of  ensilage 'in  milk  is  mainly 
due  to  what?  176.  What  effect  has  rye  pasture  (when  headed 
out)  upon  the  taste  of  milk?  Why?  177.  Explain  the  effects 
of  wild  mustard,  garlic,  turnips,  and  rape  upon  the  taste  of 
milk  ?     178.  How  is  the  flavor  produced  ?     179.  What  is  formed  ? 


INDEX. 

Page. 

ACID  in  milk 36 

Acidimeasure i7 

Acid,  sulphuric 20 

Aerating  milk 89 

Albumin 5>  59 

Alkali  test  for  acid 36 

Alkali  solution 36 

Apparatus  for  measuring  acid 21 

Ash  of  food-stuffs 127 

Ash  of  milk • 3.78 

BABCOCK  milk  test 16 

Babcock  test,  reliability  of 14 

Babcock  test,  reading  the  fat - 18 

Babcock'Sjjformula  for  solids 4° 

Babcock  test-bottle i? 

Balanced  rations 125 

Balanced  rations,  effect  on  butter 120 

Beimling's  milk  test "2 

Bulky  rations ^34 

Butter ^14 

Butter  colors 83 

Butter,  composition  of 53 

Butterine ^^4 

Buttermilk,  composition  of no 

Butter,  water  in 54 

Butter  yield  and  milk  fat • 73 

Butter  and  cheese,  comparative  amounts  made  from  milk 73 

Butyric  acid 83,  96 

Butyrin 29 

Butyrometer,  Gerber's i" 

CALCULATING  rations 132 

Caprion ^9 

Caprylin  ^9 

Casein  of  milk 3.  58 

Centrifugal  action 20 

Centrifugal  machine • 18 

Changes  during  transportation  of  milk 87 


Cheese 


114 


Cheese-making ^2 

Cheese-making,  distribution  of  milk  solids  in 54 


INDEX.  153 

Cheese-making  from  rich  and  poor  milks 67 

Churning 52 

Citric  acid  in  milk ^8 


Cochrane's  method. 


"3 


Cold  deep  setting  process 48-50 

Color  of  milk 83 

Colostrum  cells 80 


Colostrum  milk 


79 


Composite  test 22 

Composition  of  American  fodders 138-140 

Composition  of  butter 53 

Composition  of  milk 6,  7 

Concentrated  rations 134 

Condensed  milk 103 

Cooling  of  milk  before  setting 88 

Cost  of  fodders 135 

Cost  of  fodders,  table  of 141 

Cream,  composition  of 46 

Cream  raising  by  dilution 90 

Cream  testing 46 

Curing  room 70 

DELAYED  setting  of  milk 88 

Dividends,  making  of 74 

Dry  matter  of  milk 2 

ETHER  extract 128 

FAT  globules  of  milk - 8 

Fat  globules,  size  of 8 

Fat,  loss  of,  in  butter-making 47 

Fat  of  milk 27 

Fats,  food  value  of 30 

Fat,  testing  cheese  for 68 

Fat,  the  production  of 125 

Fatty  acids 29 

Fermentation  of  milk  sugar 33 

Ferser's  pioscope 113 

Fiber,  crude 129 

Fibrin  in  milk 81 

Filled  cheese 114 

Filled  cheese,  detecting 1 14 

First  or  fore  milk 10 

Flavors,  desirable  and  undesirable  ones  in  butter 122 

Fodders,  cost 135 

Food,  effect  of  on  quality  of  butter 119-121 

Food,  requirements  of  different  animals 135 


154  INDEX. 

Frozen  milk 24 

GASES  in  milk 82 

Gerber's  butyrometer 112 

Glycerine 29 

Grains,  composition  of 140-142 

HARD  butter,  production  of 119 

Hay,  composition  of 139,  144 

Heat  produced  from  foods 126 

Heat  units 122 

Hehner  &  Richmond's  formula 44 

Hot  iron  test 61 

Hygrometer 71 

IODINE  number 31 

LACTIC  acid 33,  34 

lactic  acid,  determination  of 34 

Lactic  acid  organisms 33 

Lactocrite 112 

Lactometer 40,  41 

Lactometer,  table  for  correct  readings 145,  146 

Lactoscope 113 

Losses  of  fat  in  butter-making 51 

MARE'S  milk 96 

Measuiing  the  milk  with  the  pipette 16 

Milk,  composition  of 2,  6,  7 

Milkfat 5.27 

Milk  from  diseased  cows 93 

Milk  serum 2 

Milk  sugar 33 

NITROGEN-FREE  extract 129 

Nitrogenous  compounds  of  fodders 127,  129 

Nitrogenous  compounds  of  milk 58 

Non-nitrogenous  compounds  of  fodders 127,  128 

Nutritive  ratio 131 

OLEIC  acid 29 

Olein 28 

Oleoma rgarin 28,  114 

Oleomargarin,  digestibility  of 116 

Oleomargarin.  testing  for 114 

PALMITIC  acid 29 

Pal  matin 28 

Pasteurizing  of  milk loi 

Paying  for  milk  by  test 72 

Percentage  composition  and  totaJ  yield  of  milk  . .  ^ 9 


INDi:X.  155 

Pioscope J 

Pipette  for  measuring  milk j^ 

Potassium  bichromate  used  in  composite  test 2^ 

Preservatives 

Preserving  milk j^^ 

Proteids  of  milk ^g 

Protein  of  food,  importance  of j.^ 

QUESTIONS j^g 

Quick  ripening  cheese , »q 

RATION,  standard ^^2 

Reading  the  fat jg 

Rennet .'    g^ 

Renn et  test ^ 

Ripening  cream ^^ 

Ripening  of  cheese gq 

Roots  in  rations 

134 

Roots,  compostion  of 1^0-142 

Rye  fodder,  effects  on  taste  of  milk ,„_ 


SAI,T 


86 


Sampling  milk j, 

Sanitary  condition  of  milk.   q,   „. 

Saponification  of  fats -^ 

Separator .g 

Shallow  setting  of  milk .g 

Sheep's  milk __ 

Short's  method , jj2 

Silage,  effects  upon  milk j2j 

Silage  in  ration j, . 

Simple  method  for  testing  milk jj^ 

Skim-milk,  composition  of jo6 

Skim-milk  from  separator jon 

Skim-milk,  feeding  value jo7 

Skim-milk  test-bottle 24 

Sodium  hydroxide  solution ,5 

Soft  butter,  production  of j20 

Solids  of  milk 2 

Solids  of  milk  serum jj 

Sour  skim-milk,  feeding  of 107 

Sow's  milk ^5 

Specific  gravity  of  milk 40 

Standard  ration 1^2 

Starter  or  culture  for  ripening  cream 35 

Stearic  acid 29 

Stearin 28 


156  1  INDEX. 

Sterilization  of  milk 100 

Strippings  10 

Sugar  in  milk 5 

Surface  tension 8 

TABLES 138-146 

Test-bottle 17 

Test-bottle  for  skim-milk 24 

Test-bottle  for  cream 47 

Testing  cream 46 

Testing  milk 14 

Testing  cheese  for  fat 68 

Testing  test-bottles 19 

Total  solids  of  milk 2 

Total  yield  of  milk 9 

Tyrotoxicon 80,  108 

UREA  in  milk 81 

VOLATILE  fatty  acids 116 

WATER  in  food-stuffs 1 26 

Water  in  butter 53.  54 

Water  in  cheese 66,  67 

Water  in  milk 2,  6,  7 

Watered  milk 43 

Weeds,  effect  on  taste  of  milk 122 

Whey,  composition  of 109 

Whey,  feeding  value  of 109 

Whey,  testing  for  fats 69 


norsuTT  imAKT 

fi.  C.  State  College 


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ONONDAGA  POTTERY  CO. 
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Syracuse,  N.  Y.,  Dec.  12, 1896. 
Mr.  Ernest  Mayer,  New  Brighton,  Pa. 
Dear  Sir  : 

******"  In  regard  to  I^angenbeck's  book, 
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^         EMSTOIN,  F»/\. 

Strictly  Chemically  Pure  fluriatic, 

Nitric,  and  Sulphuric  Acids  and  Ammonia, 

Chemically  Pure  Salts. 


